The Diamond Rainbow: Fancy Colored Diamonds

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Aurora Butterfly of Peace The colored diamonds in the Aurora Butterfly of Peace were assembled over a 12-year period by Alan Bronstein and Harry Rodman of Aurora Gems Inc., New York. The butterfly’s 240 stones show nearly the full spectrum of color and cut styles of naturally colored diamonds. - Courtesy Alan Bronstein

Aurora Butterfly of Peace
The colored diamonds in the Aurora Butterfly of Peace were assembled over a 12-year period by Alan Bronstein and Harry Rodman of Aurora Gems Inc., New York. The butterfly’s 240 stones show nearly the full spectrum of color and cut styles of naturally colored diamonds. - Courtesy Alan Bronstein

When diamonds are graded in what is considered the "normal" color range they are measured on a colorless through light yellow scale. This color is described using the industry standard D-to-Z color-grade scale; however, some diamonds surpass this scale and display a color beyond the Z range, or diamonds that display any other color face-up. These diamonds are what we call fancy color diamonds. These rare diamonds come in every color of the rainbow, including: blue, green, pink, and red.

HOW COLOR HAPPENS

When light enters into a diamond the stone absorbs some of the wavelengths (spectral bands) and returns the others back to our eyes. The color that we see is a combination of these unabsorbed wavelengths. For example: if little or no absorption occurs, all of the wavelengths are returned to the eye and the diamond will appear colorless; if all the colors are absorbed, we will see black. 

There are two main things that influence the way a diamond absorbs light and determines its color. One is impurities: atoms other than carbon in the crystal lattice; the second is structural defects: defects include missing carbon atoms or distortions in the crystal lattice. Both impurities and structural defects affect the color you see by changing the way a diamond absorbs light.

Structural defects that cause color are called color centers. (Color centers may also be caused by a combination of structural defects and impurities.) The defect creates an opening in the crystal lattice that is then filled by the impurity element. Nitrogen is the most common element to fill these gaps, producing a yellow color. Distortions in the crystal lattice can also create color centers. For example, a strain can develop along growth lines while a crystal is forming, causing more or different light waves to be absorbed. This often produces pink and brown colors. 

FANCY COLORED DIAMONDS

Fancy color diamonds are less common than diamonds in the normal range and come in almost any color you can imagine. As mentioned earlier, diamonds in the normal color range are graded on a D-Z color scale. Generally speaking the further along in the alphabet the color is the less monetary value the diamond has. This is not the case with with most fancy colored diamonds; their value increases as their color increases. Red, green, purple, and orange are generally the most rare, followed by pink and blue. Yellows and browns are the most common fancy colors, but they’re generally less valuable than the rarer colors. 

Pink, Red, Purple, and Orange: 

Diamonds that fall in the red ranges (red, pink, purple, orange) are extremely rare and have a premium value. In this category the more "pure" the color the higher the value. For example a true pink would be worth more than one that had a brownish, or orangey tint. The leading producer of pink diamonds is currently Australia's Argyle mine. They also produce beautiful red and purple diamonds. Pure orange diamonds (without a hint of brown) are the rarest of all the diamond colors. 

The color pink is due to graining (strain) inside the diamond crystal. This distortion is believed to also cause the red color. The cause of the color orange is still somewhat of a mystery though scientists believe that it is a combination of chemical impurities and structural distortions. 

The Williamson Diamond was discovered in October 1947 at the Mwadui mine in Tanganyika, owned by the Canadian geologist and royalist Dr. John Thoburn Williamson, for whom the diamond was named. The 54.5 carat uncut stone was presented by Dr Williamson as a wedding present to the (then) Princess Elizabeth in 1947. The firm of Briefel and Lemer of Clerkenwell were entrusted with cutting the diamond and subsequently turned the rough into a 23.6-carat round brilliant, a cut that was chosen to show off its rose color. Queen Mary and Princess Elizabeth made a point of visiting the Clerkenwell based firm and inspected the work of cutting and polishing of the stone on March 10th, 1948. The pink stone was set as the center of a brooch in the form of a jonquil flower (narcissus), designed by Frederick Mew of Cartier, in 1953. Dr Williamson also gifted 170 small brilliant-cut diamonds, 12 baguette-cut diamonds and 21 marquise diamonds, which were used to form the petals, stalk and the leaves of this brooch.

Green:

Fancy green diamonds are typically not intensely saturated. They are usually light in color and often have a gray or brown cast to them. Green diamonds are interesting in that their color rarely extends much below the surface of the stones. Cutters must be creative in their cutting so as to retain as much of the color as possible. You may also see an excess of natural rough on the girdle (facet that goes around the circumference of the stone) for this reason as well. Green diamonds are a product of radiation, either natural or man made. Radiation essentially displaces atoms from their normal positions in the crystal lattice. Natural green diamonds are extremely rare.

The most famous natural green diamond is the Dresden Green diamond.  The diamond's first recorded purchase was in 1726 by Friedrich Augustus I (Augustus the Strong), King of Poland and Elector of Saxony. The stone was housed Dresden Palace in Germany near the river Elbe. The stone took its place in the palace's west wing in an area known as the Green Vaults, a green walled room built to house state treasures. The Dresden Green stayed in the palace for most of its recorded history save for a few times when it was relocated. One of these times saved the stone from destruction during Word War II, since most of the palace and the vaults were destroyed. Today the Dresden Green may be seen on display in Germany in the eighth room of the reconstructed Green Vaults. 

Because the Dresden Green has such a long history we know for a fact that its color predates experiments with artificial irradiation (1904). This means that it is the perfect candidate for study. Analysis of the Dresden Green gave GIA research scientists the opportunity to test the criteria that they had developed to determine if a green diamond’s color is natural or treated. However, after their initial testing, scientists determined that even more research is needed to investigate the complex nature of natural green diamonds and their irradiated counterparts.  Progress is slow, but work continues. 

Blue: 

Blue diamonds are also extremely rare. As with green diamonds they usually are not highly saturated and have a hint of gray to them. The most famous blue diamond in the world, the Hope Diamond, was graded as a Fancy Deep Grayish Blue

The cause of the color blue in most natural blue diamonds is boron impurities. In a few rare cases blue may also be caused by natural radiation that was present when they were forming. In very rare cases hydrogen can cause a grayish blue color. 

The Tavernier Blue was the original diamond from which the Blue Diamond of the French Crown (aka the French Blue), and eventually the Hope Diamond would come. In 2005 historians and gemologists scientifically proved that this stone was 115.16 carats and a Type IIb (boron containing diamond).

The stone was originally described by 17th century gemstone trader and traveler Jean-Baptiste Tavernier. He described the stone as "violet" in color and possessing of perfect clarity. Taverneir frequented India in search of gemstones for trade, so it is not a stretch to assume that his documented accounts of the diamond having an Indian origin are true. The stone then ended up in the hands of Louis XIV of France. The Tavernier Blue was re-cut by court jeweler Jean Pitau into the 68-carat French Blue which the king had  set on a cravat-pin. 

In 1749 Louis XIV's great-grandson, King Louis XV, had the French Blue set into a more elaborate pendant for the Order of the Golden Fleece. The piece created by court jeweler André Jacquemin included a 107 carat red spinel dragon. In 1792, during the tumultuous times of the French Revolution the stone was stolen from the French Crown. The stone then reemerged having been cut into the 45.52 carat Hope Diamond in an attempt to veil its identity. After a long history that includes the stone traveling far and wide the Hope diamond finally came to rest at the Smithsonian Institution where it can be seen on display. 

Another prized blue diamond is rumored to have been taken from the Tavernier. This stone was originally set as a ring for Empress Maria Feodorovna, wife of Russian Emperor Paul I. It was given to the State Diamond Fund in 1860 by her daughter-in-law, the Empress Alexandra Feodorovna. The diamond was mounted into a stickpin. Currently the 7.50 carat stone is preserved in the collection of the Alexander Palace in Tsarskoye Selo, Russia. The provenance of this Russian stone is still disputed.

Brown:

Brown is the most common of the fancy colored diamonds, it has also been one of the least popular color of diamonds in recent times. This is because brown diamonds have been typically seen as "impure" (sometimes mistakenly thought to be colored by inclusions) and considered to only be good for industrial uses. Brown diamonds are in fact no more "impure" than pink diamonds. Both owe their color to internal graining (strain). If there is also nitrogen present then the stone will have a brownish yellow color. 

In the 1980's brown diamonds were being found in abundance at the Argyle mine. In an attempt to stir public interest they gave the various colors descriptive names like "cognac" and "champagne." Brown diamonds range in colors from very light to very dark, and many have modifying tones of yellow, orange, or red. Today brown diamonds are available in high end jewelry as well as more commercial products. 

At 407.48 carats, the fancy brownish yellow diamond, internally flawless (IF) Incomparable Diamond is the 3rd largest faceted diamond in the world. The name Incomparable was given to this diamond by its owners, the Zales Corporation (a Dallas, Texas based jewelry store chain) who initially purchased the enormous 890 carats rough diamond from De Beers. The diamond was displayed for the world in November 1984, to coincide with the 75th anniversary of the Zale Corporaion. The cut of the diamond is described as a shield-shaped step cut. The diamond was also put on display at the Smithsonian Institute's Natural History wing.  The stone was put up for auction twice but failed to sell. It is believed to be currently held by a private individual. 

Yellow:

Yellow is the second most common of the fancy colored diamonds. The color in yellow diamonds is usually the result of the presence of nitrogen, though some brownish yellow diamonds have also been found to contain hydrogen. A common descriptive sales term for bright yellow diamonds is "canary". 

The Cora Sun-Drop Diamond is the largest known yellow pear-shaped diamond, weighing 110.3 carats. It was sold for $10.9 million at Sotheby’s auction in Geneva and set a world record price for a yellow diamond. It was found in South Africa in 2010 within a kimberlite pipe. Tests show that the diamond was formed between 1 and 3 billion years ago. Nitrogen impurities in the carbon crystal structure give the diamond its yellow color as they modify light, absorbing the blue part of the visible spectrum.
The stone was cut by New York based Cora International. The Sun-Drop was unveiled to the world at London’s Natural History Museum where it was exhibited in the famous ‘Vault Gallery’ from February through August 2011. In November 2011, it was sold at an auction to an anonymous phone bidder.

The Oppenheimer Diamond is one of the most famous and largest uncut diamonds in the world. The stone is a nearly perfectly formed octahedron crystal weighing 253.7 carats. It was discovered in the Dutoitspan Mine, Kimberley, South Africa, in 1964. The stone was acquired by Harry Winston who presented it to the Smithsonian Institution in memory of Sir Ernest Oppenheimer.

The Tiffany Yellow Diamond is one of the largest yellow diamonds ever discovered. The rough stone from which it was cut weighed 287.42 carats. The Tiffany Yellow was discovered in 1878 in the Kimberley mine in South Africa. The stone was purchased by New York jeweler Charles Tiffany. His gemologist, George Frederick Kunz, studied the gem for a year before it was cut. When cutting was finished the now cushion shape weighed 128.54 carats. The yellow stone was later set by Tiffany designer Jean Schlumberger in its current setting "Bird on the Rock".

The diamond is known to have been worn by only two women: Mrs. Sheldon Whitehouse at the 1957 Tiffany Ball held in Newport, Rhode Island wore it mounted for the occasion in a necklace of white diamonds, and Audrey Hepburn in 1961 publicity photographs for the film Breakfast at Tiffany's.

White & Black:

As opposed to "white" diamonds in the normal color range fancy white diamonds have a milky white color appearance. This milky almost opalescent look is caused by submicrscopic inclusions that scatter the light entering the stone.

Black diamonds did not see popularity until the 1990's. Most black diamonds end up as industrial grit since they are usually heavily knotted crystals or an aggregate that is nearly impossible to cut. When they are seen, they are usually small melee accent stones in pave settings. One noteable exception is the Black Orlov diamond.

The Black Orlov is a 67.50 carats black diamond that is supposedly named after the Russian royal family. The diamond is believed to have originally weighed 195 carats and to have been discovered in early 19th century in India. The myth surrounding the diamond says that it was supposedly one of the eyes in a statue of the Hindu god Brahma, until it was stolen by a monk. The theft then supposedly left the diamond cursed. This curse is said to have led to the suicide of diamond dealer J. W. Paris in 1932 who is said to have jumped from a skyscraper in New York City. The "curse" continued with the stone's later owners Russian princesses Leonila Galitsine-Bariatinsky and Nadia Vygin-Orlov (after whom the diamond is named). Both women are rumored to have jumped to their deaths in the 1940's. The diamond was later bought by Charles F. Winson who cut the stone into three pieces (legend says that it was done in an attempt to break the curse). One of the pieces is the 67.5 carat Black Orlov. The Black Orlov was set into a brooch surrounded by white diamonds and suspended from a necklace of more white diamonds. The diamond was then purchased by diamond dealer Dennis Petimezas in 2004; Petimezas told The Guardian in 2011 that he was "pretty confident that the curse is broken". The Black Orlov has been displayed at the American Museum of Natural History in New York City and the Natural History Museum in London.

The Colorful World of Topaz

I have always thought it was a shame that the general public has been forced into the misconception that topaz is merely and inexpensive blue gem. Incidentally the blue color is hardly ever natural: It’s almost always caused by treatment. Topaz has a far broader and more colorful story to tell gemstone lovers. 

Topaz is allochromatic. This means that the color you see is caused by an elemental impurity or defect in its crystal structure rather than by an element of its basic chemical composition. For example, the presence of the element chromium causes natural pink, red, and violet-to-purple colors in topaz. Imperfections at the atomic level in topaz crystal structure can cause yellow, brown, and blue color. Brown is a common topaz color, and the gem is sometimes mistakenly called “smoky quart

THE 97.45-CARAT BLAZE IMPERIAL TOPAZ IS IN THE COLLECTION OF THE FIELD MUSEUM OF NATURAL HISTORY. - (PHOTO: "GEMS AND GEMSTONES: TIMELESS NATURAL BEAUTY OF THE MINERAL WORLD" BY GRANDE & AUGUSTYN, U OF CHICAGO PRESS.)

Topaz actually has an exceptionally wide color range that, besides brown, includes various tones and saturations of blue, green, yellow, orange, red, pink, and purple. Colorless topaz is plentiful, and (as was mentioned earlier) is often treated to give it a blue color.
The color varieties are often identified simply by hue name—blue topaz, pink topaz, and so forth—but there are also a couple of special trade names. Imperial topaz is a medium reddish orange to orange-red. This is one of the gem’s most expensive colors. Sherry topaz—named after the sherry wine—is a yellowish brown or brownish yellow to orange. You may hear stones in this color range are referred to as "precious topaz". This term is used to distinguish them from less expensive citrine (yellow quartz) and smoky quartz.

 

TOPAZ CRYSTALS ARE TYPICALLY ELONGATED, WITH GROOVES PARALLEL TO THEIR LENGTHS. FOR THIS REASON, THEY'RE COMMONLY CUT INTO LONG OVAL OR PEAR SHAPES. THESE CRYSTALS SHOW ORANGE, PINK, AND BROWN COLORS. - ERIC WELCH/GIA

What is Imperial Topaz?

Red is one of the most prized and rare topaz colors. Red represents less than one-half of 1 percent of facet-grade material found. The color known in the gem the trade as "imperial topaz" is even more highly prized and rare. They color is a bit elusive and subjective; however, many dealers insist that a stone must show a reddish pleochroic color to be called imperial topaz. The reddish pleochroic color often appears at the ends of fashioned gems—like pears and ovals—that have an otherwise yellow-to-orange bodycolor. This look is illustrated in the images below. 
The name for "imperial topaz" originated in nineteenth-century Russia. At the time, the Ural Mountains were topaz’s leading source, and the pink gemstone mined there was named to honor the Russian czar. Ownership of the gem was restricted to the royal family.

THIS UNTREATED 45-CARAT IMPERIAL TOPAZ DISPLAYS AN ATTRACTIVE REDDISH PEACH COLOR. (PHOTO: CONSTANTIN WILD, IDAR-OBERSTEIN)

SPECTACULAR PRIZE-WINNING, ORANGY-RED, FLAME-SHAPED IMPERIAL TOPAZ GEM. (PHOTO: GEM COURTESY OF JOHN DYER & CO.)

Bohemian Garnets

This Brooch Dates From the Third Quarter of the 19th Century. (Photo Courtesy the National Czech & Slovak Museum & Library)

This Brooch Dates From the Third Quarter of the 19th Century. (Photo Courtesy the National Czech & Slovak Museum & Library)

“Bohemian garnets” are garnets mined in an area once known as Bohemia (it often refers to the entire Czech territory, including Moravia and Czech Silesia). They are the variety of garnet called pyrope (from the Greek words pyr for “fire” and ops for “eye”). Those found in Central Bohemia (in the north of the Czech Republic) are considered to be of the highest quality. 
The Bohemian garnet has been mined for over 600 years mostly dug at the mines of Meronitz, and chiefly in the northwestern part of the Czech Republic. The garnets are found in a gravel or conglomerate, resulting from the decomposition of a serpentine. Sometimes, however, they are found in the matrix. When this happens they are often associated with a brown opal. Most of the good quality the stones are small with those as large as approximately 1/4 inch and above being reported rarely. By the 19th century it was determined that the elements creating the intense red color in pyrope were Chromium and Manganese. The color ranges from fiery-red to ruby-red. The Bohemian garnet also possesses excellent clarity, transparency, and has a high refraction of light. This means that the stone has a remarkable sparkle and what has been described as an "inner glow".

The stone gained popularity in Europe in the 18th and 19th century also becoming a favorite of the Victorians. Traditional Bohemian design placed it's emphasis on the arrangement of the garnets, taking precedence over the metal chosen for a piece of jewelry. George Frederick Kunz cites in his book Rings for the Finger Garnet that rings were generally made of faceted, rose or cabochon cut Garnets in 14 or 18 kt gold. By the late 19th century larger Pyropes were typically brilliant-cut, resulting in very bright (red) stones, whereas the very small stones were usually rose-cut. 

This Art Nouveau Style First Appeared in Individual Creations of Designers Rather Than in Industrial Mass Production. (Photo Courtesy The National Czech & Slovak Museum & Library)

An Example of the Mass Produced Items Typical of the Bohemian Garnet. (Photo Courtesy The National Czech & Slovak Museum & Library)

An Example of the Mass Produced Items Typical of the Bohemian Garnet. (Photo Courtesy The National Czech & Slovak Museum & Library)

The introduction of larger scale manufacturing of garnet jewelry created mass-produced machine pressed metal settings and garnets of inferior quality. The majority of readily available "Bohemian Garnet" antique jewelry falls into this mass production category. While these pieces are beautiful in their own right, it should be noted that like any piece of jewelry rarity and individuality are valued much more highly. 

Antique Pyrope Hairpin From the Smithsonian


Tantalizing Tourmaline

rainbowoftourmaline

Tourmaline by Sandy Hoy

October's birthstones are truly spectacular. 
Along with opal, tourmaline is October's birthstone. Both of these stones are gorgeous, but tourmaline is what I want to focus on today. For too long, tourmaline has only been seen as the dull green that is widely available. This is a shame. Tourmaline comes in such a wonderful wide range of colors and with a Mohs hardness of 7 to 7.5, it is durable enough to be used in any type of jewelry.

green tourmaline

History
The first tourmaline was recorded in the 1500's in Brazil by a Spanish conquistador. The conquistador confused the vivid green of the tourmaline with that of the emerald. His mistake was not revealed until the 1800's when tourmaline was formally recognized as a distinct mineral species.
The name tourmaline comes from the word toramalli, which means “mixed gems” in Sinhalese (a language of Sri Lanka).  Dutch merchants started using the name to identify the multicolored, water-worn pebbles that miners found in the gem gravels of Ceylon (now Sri Lanka). The stones were brought to Europe in vast amounts by the Dutch East India Company as the demand for gemstones increased. As stated earlier, it was not until the 1800's when scientists were able to positively identify tourmaline as its own mineral species. As with many gemstones until the development of modern mineralogy, a stone's identity was based solely on its coloring, resulting in many stones being misidentified throughout time as ruby, sapphire, emerald, and so forth.

tourmalinefacts

One of the earliest reports of tourmaline in the United States was in California in 1892. In the late 1800s, Tiffany gemologist George F. Kunz worked to make tourmaline an American gem, praising the tourmaline deposits of Maine and California; however, it was not the American market that the tourmaline mines both in the United states and in the Himalayas ended up attracting: it was the Chinese market. 
Because the miners became so dependent on Chinese trade, when the Chinese government collapsed in 1912 the US tourmaline trade collapsed with it. The California mines stopped or moved to sporadic production. Today, mines in San Diego County such as the Stewart Lithia mine at Pala still produce a small supply of gem-quality tourmaline.
The tourmaline trade expanded again during the first half of the twentieth century, when Brazil began to mine large deposits with superb quality. In the 1950s, additional finds were uncovered in other countries around the world, including Madagascar and Afghanistan which have have produced a stunning red tourmaline.

Pink tourmaline from Pala Mountain, Stuart Mine, San Diego. (Photo: Jeff Scovil)

Pink tourmaline from Pala Mountain, Stuart Mine, San Diego. (Photo: Jeff Scovil)

Tourmaline Locations and Mining
Gem and specimen tourmaline is mined chiefly in Brazil and Africa. Additional locations include Sri Lanka, Tanzania, Nigeria, Kenya, Madagascar, Mozambique, Namibia, Afghanistan, Pakistan, and Malawi. Tourmaline is also sparsely mined in the San Diego County area of California.
Tourmaline (and some other large crystal gemstones) generally occur in an extreme form of igneous rock known as a pegmatite formation. Pegmatite is a type of igneous rock that forms during the last stages of magma cooling. Large crystals are fairly common in many types of igneous rock formations usually due to a slow rate of crystallization. With pegmatites, large crystals are attributed to low-viscosity fluids that allow the chemicals that make up a crystal to be highly mobile on an atomic level.
During the early formation of pegmatites, the magma usually contains a large amount of dissolved water and other chemicals such as chlorine, fluorine and carbon dioxide. Water is not removed during the early magma crystallization, so it becomes more concentrated as the crystallization continues. The presence of the water eventually forms large pockets in the rock. These super heated water filled pockets are also rich in the atoms of various chemicals. Within the pockets, the atoms have a much greater space to expand into than would be present elsewhere. This space combined with the extreme heat allows them to rapidly form into large crystals. The extreme conditions of crystallization in pegmatites have sometimes produced crystals that are several meters in length and weigh over one ton. 


The Colors of Tourmaline
Tourmalines make up a group of closely related mineral species that share the same crystal structure but have different chemical and physical properties. They share the elements silicon, aluminum, and boron, but contain a complex mixture of other elements such as sodium, lithium, calcium, magnesium, manganese, iron, chromium, vanadium, fluorine, and sometimes copper. It is these alterations to a tourmaline's chemical composition that directly influences its physical properties, including color. 


Many tourmaline color varieties have inspired their own trade names:

  • Rubellite is a name for pink, red, purplish red, orangy red, or brownish red tourmaline, although some in the trade argue that the term shouldn’t apply to pink tourmaline.
  • Indicolite is dark violetish blue, blue, or greenish blue tourmaline.
  • Paraíba is an intense violetish blue, greenish blue, or blue tourmaline from the state of Paraíba, Brazil.
  • Chrome tourmaline is intense green. In spite of its name, it’s colored mostly by vanadium, the same element that colors many Brazilian and African emeralds.
  • Parti-colored tourmaline displays more than one color. One of the most common combinations is green and pink, but many others are possible. Including "watermelon" and Liddicoatite. 
Liddicoatite was first recognized as a separate mineral in 1977. The mineral was named in honor of Richard T. Liddicoat (March 2, 1917 – July 23, 2002), the second president of GIA who is often referred to as the “Father of Modern Gemology.” Most liddicoatite comes from Madagascar, including this slice from the Anjanabonoina pegmatite. Coutresy Harvard Mineralogical Museum, photo by Robert Weldon/GIA

Liddicoatite was first recognized as a separate mineral in 1977. The mineral was named in honor of Richard T. Liddicoat (March 2, 1917 – July 23, 2002), the second president of GIA who is often referred to as the “Father of Modern Gemology.” Most liddicoatite comes from Madagascar, including this slice from the Anjanabonoina pegmatite. Coutresy Harvard Mineralogical Museum, photo by Robert Weldon/GIA

Photo courtesy of GIA

Photo courtesy of GIA

Some tourmalines have a striking cat’s-eye effect called chatoyancy. Cat’s-eye tourmalines are most often green, blue, or pink. The "eye" often has a softer and more diffused than than other stones that display the same effect. This is due to the multitude of thin, tube-like inclusions inside the stone. The inclusions are larger than the inclusions of other stones, such as a cat’s-eye chrysoberyl, so the "eye" isn’t as sharp. Like other cat’s-eye stones, tourmaline needs to be cut as a cabochon to show the effect.

What's in a name? Paraíba Tourmaline

One of the most coveted and expensive of the varieties mentioned above is Paraíba.  It is a relatively "young" gemstone in that it was not discovered until the 1980, but its vivid blues hold the attention of the entire gem world. The reason behind the vivid colors is in fact why a true Paraiba stone is so rare and special. 
Normally, iron, manganese, chrome and vanadium are the elements responsible for the beautiful colors of tourmaline. The Paraíba tourmaline is different: its color is due to copper, an element which had never before been seen in a tourmaline. The presence of copper in the stone is as much what defines the tourmaline as a Paraíba as the location from which it came. Copper in high concentrations is responsible for the coveted radiant blue, turquoise, and green hues. 

Scientists have also (relatively recently) discovered that Paraíba tourmaline may also often contain manganese as well. When both of these two elements are present they produce a variety of vivid colors such as: emerald green, turquoise to sky blue, sapphire blue, indigo, bluish-violet, and purple. They can also result in more muted pale grey to violet-blue tones. 
Because of the stone's high value in an uncut state, Paraíba tourmalines are almost always custom cut to retain as much of the stones weight as possible, however the stones are still in sizes bigger than one carat. 

The flawless 191.87 carats Paraiba tourmaline, The Guinness World Records largest, has been placed by experts in the field amongst the world’s rarest gems.

Recently scientists have discovered that Paraíba tourmaline often also contain manganese and it is the interplay between these two elements that creates the coveted colors. 

Recently scientists have discovered that Paraíba tourmaline often also contain manganese and it is the interplay between these two elements that creates the coveted colors. 

Since the late 1980s, the Paraíba area of Brazil has been a source of a strikingly colored variety of tourmaline called Paraíba tourmalines.

Since the late 1980s, the Paraíba area of Brazil has been a source of a strikingly colored variety of tourmaline called Paraíba tourmalines.

With Paraíba, the key factor is not size, but color; all factors being equal, the stone with the better color is a better choice.
During Paraíba tourmaline’s brief history, the gem has always been extremely scarce. However, new discoveries of copper-bearing tourmalines that resemble the vibrant, intense colors of the gems found in Brazil’s Paraíba region have also been found in other parts of the world. An article in the Spring 2008 issue of GIA’s Gems & Gemology scientific journal described copper-bearing gems present in Mozambique. Nigeria has become a source of these striking gems as well. With these new sources there comes the possibility that viable, commercial sources of this rare copper-bearing tourmaline might provide a larger supply of material. This brings a new problem for the niche Paraiba trade. If the stones of the same chemical composition and quality are being found outside of Paraiba does the trade name still apply? Only time and the market will tell. I personally think that the romance of a trade name should have little to do with the stone you are buying. The romance of a trade name aside, if the quality is good and the color is vibrant then that is what we should judge a stone by. 

The Lily Safra poppy flower brooch with diamond and tourmalines sold for $1,273,320 at Christie's Geneva, 5/14/2012. - © Christie's Images/The Bridgeman Art Library

The Lily Safra poppy flower brooch with diamond and tourmalines sold for $1,273,320 at Christie's Geneva, 5/14/2012. - © Christie's Images/The Bridgeman Art Library

The rainbow of colors that tourmaline has to offer the wearing is truly impressive. This stone has something to offer for everyone.  


 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Sunset Sapphires: Padparasha

Sunset by Harry Winston, padparadscha sapphire and diamond ring.

Sunset by Harry Winston, padparadscha sapphire and diamond ring.

On this final day of September it is only fitting to talk about one of the rarer and most sought after sapphire colors: the padparascha. 
Padparadscha is a color of sapphire that is commonly portrayed as a mixture of orange and pink colors. It has been referred to as a marriage between the color of sunset and that of a lotus blossom.  Padparadscha sapphires are considered among the most beautiful and valuable of the corundum gems. Prices for padparadschas vary greatly according to size, quality, and presence of treatments. At the top end, they may reach as much as US$50,000 per carat or more.
However the history of what actually defines a sapphire as a padparascha has changed over time and the question of just what qualifies a sapphire as a “padparadscha” is a matter of hot debate, even among experts.

Location: The original locality for padparadscha was Sri Lanka (Ceylon) and many purists today believe the term should be restricted only to stones from Ceylon. However, fine stones have also been found in Vietnam’s Quy Chau district, Tanzania’s Tunduru district, and Madagascar. Stones from each of these areas are often heat-treated and this is done at fairly low temperatures (1200°C and below) and such heat treatment is not always detectable.  Because of this diverse group of localities and the ease of treatments, many have come to rely on color as the defining characteristic of the padparascha sapphire, but here too we find debate and inconsistencies.

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The Color Debate: The term padparadscha is actually a corruption of the Sanskrit/Singhalese padmaraga (padma = lotus; raga = color), a color similar to the lotus flower (Nelumbo Nucifera ‘Speciosa’). The padparadscha was born about twenty centuries ago, it is obvious
that over a period of about eighteen centuries men have built an idea of the padparadscha that has
varied considerably according to interests, periods and places. For instance, a number of the Lotus (Nelumbo nucifera [Nelumbium Speciosum indica] ) varieties and their respective colors have changed or ceased to exist over the years, leading to variations in what may constitute a "lotus color".

In the Western world, padparadscha has been defined as a Sri Lankan sapphire of delicate pinkish orange color; however, the delicate description of the padparadscha is not the norm in texts from the stones countries of origins. In fact, virtually all of the ancient texts that we have refer to the padparadscha as a type of ruby with the color of fire or sunset: a red-orange. In an early definition from the Indian subcontinent, dating from about 1200–1300 AD, the padparascha is described as:

That which spreads its rays like the sun, is glossy, soft to the touch (komala?), resembling the fire, like molten gold and not worn off is paümaraya [padmaraga]. - Sarma, 1984, Thakkura Pheru’s Rayanaparikkha – A Medieval Prakit text on Gemmology

Other definitions of also include references to vermilion and saffron coloring.  This paints an image of a much brighter and vibrant stone than the pastel versions that are prized today.
The jump from the vivid yellow-red coloring definition to that of the modern day criteria is linked to and  article by the GIA’s Robert Crowningshield published in 1983. Crowningshield provided an excellent summary of the origin of the term and what many considered to be ideal examples. Unfortunately, however, the GIA Library at the time did not include many Indian or Arab lapidaries.  The final definition was completely devoid of any early references to rich colors in the definition that he himself cited, but did not accept.
Crowningshield concluded by laying what we now know as the foundation for the color criteria of the padparascha:

It is clear that the term padparadscha was applied initially to fancy sapphires of a range of colors in stones found in what is now Sri Lanka. If the term is to have merit today, it will have to be limited to those colors historically attributed to padparadscha and found as typical colors in Sri Lanka. It is the GIA’s opinion that this color range should be limited to light to medium tones of pinkish orange to orange-pink hues. Lacking delicacy, the dark brownish orange or even medium brownish orange tones of corundum from East Africa would not qualify under this definition. Deep orangy red sapphires, likewise, would not qualify as fitting the term padparadscha.
Robert Crowningshield, 1983

On June 16–18 2005, members of the Laboratory Manual Harmonisation Committee (LMHC) met in Milan, Italy to consider a standardized definition of padparadscha which stands today: 

Padparadscha sapphire is a variety of corundum from any geographical origin whose colour is a subtle mixture of pinkish orange to orangey pink with pastel tones and low to medium saturations when viewed in standard daylight.
The name 'padparadscha sapphire' shall not be applied in the following cases:
If the stone has any colour modifier other than pink or orange.
If the stone has major uneven colour distribution when viewed with the unaided eye and the table up +/- 30°.
The presence of yellow or orange epigenetic material in fissure(s) affecting the overall colour of the stone.
If the stone has been treated as described in Information Sheets #2 and #3.
If the stone has been treated by irradiation.
If the stone has been dyed, coated, painted, varnished or sputtered.

In 2005, this 20.84-carat padparadscha sapphire fetched US$18,000 per carat at auction. Photo © 2005 Christie’s Images Ltd.

In 2005, this 20.84-carat padparadscha sapphire fetched US$18,000 per carat at auction. Photo © 2005 Christie’s Images Ltd.

So within these criteria where would more intense padparadscha stones exist? Questions like this are often put to the test when stunning stones like that this one from Christie's auction house are presented to the public. As is pointed out by Richard Hughes author of Ruby & Sapphire the stone would clearly fall outside the Western guidelines of what is considered a padparadscha, but would it fall outside the guidelines of the country that first defined the stone? Should there be a gradient for tones within the category? 

Questions to Ponder: Richard Hughes is a proponent of such a grading system and I have to say I am inclined to agree with him. Yes, I believe that there should be standards of color; but as he points out, there are tone and saturation variations within blue, yellow, purple, pink etc., but they are still what they are. A pale blue sapphire is still a blue sapphire, so why should a darker padparascha not be simply a more saturated darker toned padparascha. I know that this may open up a debate about the defining of colors based on the gemologist's eye, but that is nothing new to the industry. One only need look to the debates that form around a ruby and a pink sapphire call! I am also troubled by the blatant disregard for the historical and ethnographic exclusion of definitions. Is it fair that padparascha is defined by outsiders without regard for the past? 

Sri Lankan padparadscha sapphire crystal,  8 by 5 cm; Collection: Paul Ruppenthal Photo: Studio Hartmann From Gem & Crystal Treasures by Peter Bancroft

Sri Lankan padparadscha sapphire crystal,  8 by 5 cm; Collection: Paul Ruppenthal
Photo: Studio Hartmann From Gem & Crystal Treasures by Peter Bancroft

Just to make matters more confusing here is a recent description of the stone from Sri Lanka:
The term pathmaraga is a Singhalese term applied to a very special colour variety of corundum, so named after the lotus flower as its colour is sometimes akin to a variety of this flower…. The colour combination produces the rare and beautiful colour of a sunset red at its best as seen across a tropical sky.… The colour of pathmaraga is apparently a combination of yellow, pink and red, with mildly conspicuous flashes of orange.
Gunaratne and Dissanayake, 1995

Regardless of the definition the padpardscha is a beautiful stone and the gem industry will always argue because we exist in a world that is dictated by our eyes. Is there a perfect color? With the implementation of new color grading technology it is possible that we may narrow our scope further, though I secretly hope that we might actually expand it. I personally have a favorite, but I ultimately leave it to you (the consumer) since you are the ones that drive the market. Just as with any other stones, some may prefer the pastel, while others the darker. The choice is yours to make, even as the experts argue among themselves. 

Kathleen Marino MA, GG, NAJA, AJP

Special consideration: Richard Hughes author of Ruby & Sapphire; Franck Notari author of THE PADPARADSCHA SAPPHIRE from The University of Nantes


 


 

September Sapphires

Sapphire and diamond "Copacabana" ring by Chopard

Sapphire and diamond "Copacabana" ring by Chopard

sapphire rainbow

Welcome to beautiful Sapphire September! (I am a bit biased about this stone because it is my birthstone)
Sapphire is a variety of corundum. It is an oxide mineral and is a 9.0 on the Mohs hardness scale. It is an excellent for any type of jewelry. 
The name Sapphire comes from the Greek word sappheiros meaning ‘blue stone’.  But sapphires are not just blue, they come in every color of the rainbow except red. Red corundum is called Ruby. 
Trace elements such as iron, titanium, chromium, copper, or magnesium can give corundum a blue, yellow, purple, pink, orange, or green color.

Beautiful rare velvety purple 8.00ct sapphire in a platinum setting with diamond accents by  Robert Procop.

Beautiful rare velvety purple 8.00ct sapphire in a platinum setting with diamond accents by  Robert Procop.

Diamond and Golden sapphire necklace by Van Cleef & Arpels

Diamond and Golden sapphire necklace by Van Cleef & Arpels

Sardonyx

A Roman sardonyx cameo of Minerva from the Julio-Claudian period circa 1st century AD. Sold by Christie’s.

A Roman sardonyx cameo of Minerva from the Julio-Claudian period circa 1st century AD. Sold by Christie’s.

The second of August’s birthstones is sardonyx. This is a very underrated stone in my opinion. 
Sardonyx is a variety of Agate with parallel bands of white (or black) contrasting with the brownish-red (sard) body color. Because of its layered nature sardonyx stones have been and are ideal mediums for cameo, intaglio and relief carving.
Agate in turn is a variety of chalcedony which is a variety of quartz. It has a mohs hardness of 6.5-7. 
 

 

 

 

Kathleen Marino MA, GG, AJP, NAJA

Peridot

The largest cut peridot olivine is a 310 carat specimen in the Smithsonian Museum in Washington, D.C. Photo courtesy of the Smithsonian Museum

The largest cut peridot olivine is a 310 carat specimen in the Smithsonian Museum in Washington, D.C. Photo courtesy of the Smithsonian Museum

Welcome to August and a very happy birthday to all of the August babies out there! You have two great birthstones peridot and sardonyx. Here is a little about peridot.
Peridot is gem-quality olivine. Olivine is a silicate mineral and has a mohs hardness of 6.5-7. This is almost smacked dab in the middle of this hardness scale so don’t be afraid to wear it in any type of jewelry. 
Olivine in general is a very abundant mineral, but gem quality peridot is rather rare. Peridot olivine is mined in Arkansas, Arizona on the San Carlos Reservation, Hawaii, Nevada, and New Mexico at Kilbourne Hole, in the US; and in Australia, Brazil, China, Egypt, Kenya, Mexico, Myanmar (Burma), Norway, Pakistan, Saudi Arabia, South Africa, Sri Lanka, and Tanzania.
Peridot ranges in color from yellow, to yellow-green, olive-green, to brownish, sometimes a lime-green, to emerald-ish hue.

Photo courtesy of Bonhams

Photo courtesy of Bonhams

This late 19th century peridot necklace, was sold by Bonhams Auction House in 2011.

Nicholas Varnay and K2

Nicholas Varney Blue Moonstone and Diamond Earrings: Surrounded by K2, 48 carats Blue Moonstone, 0.60 carats Diamonds. 18K yellow Gold.

Nicholas Varney Blue Moonstone and Diamond Earrings: Surrounded by K2, 48 carats Blue Moonstone, 0.60 carats Diamonds. 18K yellow Gold.

A view of K2, also known as Mount Godwin Austen, in the morning sun. With a summit elevation of 8,611 meters, K2 is the second-highest mountain in the world after Mount Everest (8,848 meters), and ahead of Kangchenjunga (8,586 meters). Image © iStockphoto and PatrickPoendl.

A view of K2, also known as Mount Godwin Austen, in the morning sun. With a summit elevation of 8,611 meters, K2 is the second-highest mountain in the world after Mount Everest (8,848 meters), and ahead of Kangchenjunga (8,586 meters). Image © iStockphoto and PatrickPoendl.

One reason I love jewelry by Nicholas Varnay is that he isn't afraid of playing with "unconventional" stones.  One of the most interesting is K2 Granite,” also known as “K2 Jasper.”

What is K2 Granite? 

"K2 Granite," also known as "K2 Jasper," is an extremely interesting and actually slightly controversial rock and lapidary material that comes from Pakistan.

The mineral is a bright white granite that contains beautifully contrasting orbs of bright blue azurite. The azurite orbs can range from a few millimeters up to about two centimeters in diameter that can look like bright blue splashes on a rough pieces. 
K2 Jasper is the most commonly used name for marketing this material, but it is definitely not jasper. If you examine the rock closely you can see that the splotches are actually spherical. You will also see see cleavage faces of feldspar minerals and black flakes of biotite. 

The white granite is fine-grained: composed of quartz, white feldspars, and biotite. 
The azurite is a secondary material that clearly formed after all of the other minerals in the granite had solidified from the parent melt. This can be seen clearly during an examination of the azurite spheres. They are present along the mineral grain boundaries, within tiny fractures, and as a “dye” penetrating the feldspar grains.

I mentioned that this stone has been slightly controversial. When this mineral first appeared on the market the lapidary world did not believe that the blue splotches could be azurite (and to some extent this is still the case). This is because white granite and azurite rarely occur together. For many this is the first time that they have seen the two materials in such close association. 

The Controversy

For the last 3 or so years experienced mineralogists, people from Pakistan who have directly obtained K2 fron it's source, and lapidarists who have worked with K2 cutting cabochons, have had long discussions about the material; sharing observations, photomicrographs, chemical analyses, and x-ray diffraction data trying to learn more about the intrusive mineral, arriving at the conclusion that it is indeed azurite.  Some specimens were also found to have small areas that are stained green with malachite! The science of geology continues to evolve and astound! 

 

A piece of dry K2 Granite. A wet surface would increase the intensity of the blue azurite orbs. This piece is approximately 10 centimeters across, and the largest azurite orbs are about 1 centimeter across.

A piece of dry K2 Granite. A wet surface would increase the intensity of the blue azurite orbs. This piece is approximately 10 centimeters across, and the largest azurite orbs are about 1 centimeter across.

An oval cabochon cut from K2 Granite with several bright blue azurite stains. Within each stain you can see the texture of the granite and grains of black biotite. These indicate that the stain formed after the granite solidified from its parent melt. This cabochon is about 20 x 30 millimeters in size.

An oval cabochon cut from K2 Granite with several bright blue azurite stains. Within each stain you can see the texture of the granite and grains of black biotite. These indicate that the stain formed after the granite solidified from its parent melt. This cabochon is about 20 x 30 millimeters in size.

Where Is K2 Found? 

As stated earlier K2 granite is named after a mountain in the Karakoram Range near the border between Pakistan and China. K2, also known as "Mount Godwin Austen," is the second highest mountain in the world. The azurite granite is found in colluvium near the base of the mountain, in a very remote area visited by very few people. 

 

 

So What About Using it in Jewelry?

K2 granite cuts, tumbles, and polishes wonderfully. Due to its high feldspar content, it can be easily cut with a lapidary saw and shapes quickly on a diamond wheel. Azurite has a Mohs hardness of 3.5 to 4, however because the azurite is more of a stain within the mother mineral, the dots have the same cutting and polishing properties as the surrounding white granite. 

As to the durability in jewelry The feldspar minerals in K2 have a hardness of about 6 on the Mohs scale, therefor they can be be scratched or show signs of wear over time if subjected to extensive use, "hard wear", or impact. K2 is therefore not a good stone for mounting in a ring or bracelet, but it is a sunning (and appropriately safe) addition to the earring that inspired this article. 

Kathleen Marino M.A, G.G., AJP, NAJA

A big thanks to geology.com for their extensive research and information on the subject. Another website to visit for more information on the mineralogical makeup of K2 or other minerals is mindat.org

 

 

Zircon

We are marking the end of the year with another of December’s birthstones: Zircon

In the past when many people heard the word “zircon” (a naturally occurring gemstone) they immediately jumped to something more familiar, “cubic zirconia” (a man-made diamond simulant). In the current market, consumers have become more savvy in understanding that there is a difference; however, even though many people may have heard of zircon very few have ever encountered it.

Red Zircon Crystal, Kunar Prov., Afghanistan Photo courtesy of http://www.marinmineral.com/

Red Zircon Crystal, Kunar Prov., Afghanistan Photo courtesy of http://www.marinmineral.com/

Some gemologists classify zircons into three types—high, intermediate, and low.
The majority of zircon is generally of the low and intermediate variety. This is directly related to the chemical makeup of zircon. Zircon a zirconium silicate containing trace amounts of the radioactive minerals hafnium, uranium and thorium. Over time, these radioactive components can break down and destroy the internal lattice of the crystal (over tens of thousands of years). This leaves the zircon with an amorphous structure that has a pithy appearance. “Intermediate” zircon is also exposed to the damaging effects of radiation but to a lesser extent than low zircon.
Virtually all zircon that is used in jewelry is of the “high” variety. Zircon that is of the “high” variety is geologically “young” and virtually unaffected by radioactivity. These high zircons have full crystal structures and as a result, they have the normal physical and optical properties which are compatible with faceting. "High" zircon can also be heat treated to create colorless, blue or golden stones.

The many colors of Zircon Photo courtesy of GIA

The many colors of Zircon Photo courtesy of GIA

The stone comes in a beautiful array of colors including warm browns and lovely shades of cinnamon, sherry, yellows, oranges, and reds. The most well known of the colors are the vibrant bright blues (which may be enhanced by heat treatment). It has been estimated that approximately 80% of all zircons sold are blue, and usually command a slightly higher price. Blue topaz is often offered as a less expensive alternative.
In the early 1900s zircon was often used as a diamond simulant. Due to its doubly refractive nature, zircon displays a high amount of “fire”, even greater than that of diamond, adding to the appeal of the stone. As new technology emerged it was replaced with more convincing look-alikes including many imitations, and it’s name still brings to mind the word “imitation today”. This is sad because zircon is a beautiful stone with a wide range of colors and its own charming history and lore.  

Zircon Ring ca.1850 Photo Courtesy of the Victoria and Albert Museum

Zircon Ring ca.1850 Photo Courtesy of the Victoria and Albert Museum

"Many scholars think the stone’s name comes from the Arabic word zarkun, meaning 'cinnabar' or 'vermilion.' Others believe the source is the Persian word zargun, or 'gold colored.'  Considering zircon’s color range, either derivation seems possible.” (GIA).
In the Middle Ages, zircon was believed to aid in sleep, keep away evil spirits, and promote riches, honor, and wisdom. 

Cat's-eye Zircon Photo courtesy of GIA

Cat's-eye Zircon Photo courtesy of GIA

 
Blue zircon especially was a favorite of the Victorian Age. Zircons are usually relatively free of inclusions, but many untreated zircons may have a cloudy or smoky appearance. If it’s very noticeable, this can negatively affect price. In Victorian times, this smokiness made zircon a popular gem for mourning jewelry.
The majority of modern zircon that is used in jewelry will not have eye visible (visible to the naked eye) inclusions.  Long, parallel, visible inclusions can make the stone desirable when it is cut into a cabochon because it may create the cat’s-eye effect.

It’s a challenge to cut zircon because the gem is brittle. Cutters usually fashion zircon in the brilliant style to take advantage of its luster and fire. In the past, cutters developed a modification of the brilliant cut, known as the “zircon cut,” which uses eight extra facets around the pavilion (the gem's lower portion). In modern times this is rarely seen, as the added labor required makes it not cost effective. Zircon can also be found in step cuts (rows of parallel facets), and mixed cuts (a combination of brilliant and step-cuts). 

The fact that the gemstone has been passed over for so long is an absolute shame. Gemologist and author/researcher George Kunz (a famed gemstone buyer for Tiffany & Company) attempted to rename the stone “starlite”, owing to zircon’s high fire, to promote the gemstone. However, the name failed to catch on and over time the stone seemed to fall by the wayside. There may be a potential upside to the relative obscurity of zircon though. Analysts in the gem industry have stated that zircon has yet to reach its full potential in value, and it will only appreciate in value so it may be an excellent time to branch out and embrace the beauty of zircon.

The final word:
Zircon is Not Cubic Zirconia! Zircon is a naturally occurring mineral found in the earth. Cubic zirconia is a man-made diamond simulant. They have both been used in place of diamonds, though cubic zirconia is used much more commonly than zircon in modern times. The differences are easy for a trained gemologist to spot. When in doubt ask an independent gemologist.

Basic Information:
Formula: ZrSO4, May contain minor U, Th, Pb, Hf, Y/REE, P and others.
Crystal Systems: Tetragonal
Hardness: 7-1/2
Color: Yellow, Clear, Blue, Pink, Brown...etc
Lustre: Adamantine, Vitreous, Greasy
Mineral Group: Zircon
Major sources: Major sources of zircon are the Chanthaburi area of Thailand, the Palin area of Cambodia, and the southern part of Vietnam. 
Misc: Eye visible, strong double refractivity. This causes high fire that is more noticeable in light colored stones but may be seen even in darker stones. 

Quartz Varieties

Let's talk about something that drives me nuts. Amethyst is a purple variety of quartz. It is ONLY SHADES OF PURPLE by definition. "Green amethyst" does not exist and we need to start demanding that the proper names be used.
That being said let's run through the colors and the quartz varieties:


Green quartz = prasiolite 
purple quartz = amethyst 
purple and golden quartz = bi-color quartz, ametrine,
pink quartz = pink/rose quartz
yellow quartz = citrine 
brown quartz = smoky quartz 

black quartz = black quartz
clear quartz = rock crystal quartz or clear quartz
blue quartz = blue quartz to varieties of greenish blue, and a bright clear pink (almost always synthetic and easily identified by gemologists) 

Synthetic Quartz forms in tube shapes due to the machines used to grow them  photo courtesy of WKSU news

Synthetic Quartz forms in tube shapes due to the machines used to grow them  photo courtesy of WKSU news

Also a quick word on treated and synthetic quartz. Much of the quartz (colored varieties) you see on the market are heat treated. Heat treatment can enhance or alter the color of quartz. Treatment is difficult to detect, but it is almost always assumed. 
Over the years I have also seen a lot of synthetic quartz. It is often times cut into very large stones. There are telltale indicators of synthetic quartz (that are related to the way in which it is grown) that an experienced gemologist can quickly identify.  
Synthetic quartz is just as expensive as natural quartz varieties. The is mainly due to the fact that the majority of consumers cannot tell the difference. 

As an aside, the market for synthetic quartz has always been strange to me since quartz is one of the most plentiful gemstone materials available.

How quartz is synthetic grown     photo courtesty of voguecrystals.com

How quartz is synthetic grown     photo courtesty of voguecrystals.com

Kathleen Marino M.A, G.G., AJP, NAJA

Additional photos courtesy of: Gemselect.com, gemcutter.com, dannytherockman.com, wksu news, www.voguecrystals.net,

Turquoise: The Desert Beauty

The most traditional birthstone for the month of December is Turquoise and  the zodiacal stone for Sagittarius. Opaque, varied blue colors that has been used for centuries in jewelry and in decorative ornaments.

If cold December gave you birth,
The month of snow and ice and mirth,
Place on your hand a turquoise blue;
Success will bless whate'er you do.

Turquoise is found in various locations around world that all share the same characteristics: dry, arid, barren and possessing acidic, copper-rich ground water. This ground water creeps downward it reacts with other minerals. The product of this process is the compound of hydrated copper and aluminium phosphate known as turquoise.

The deposits of turquoise usually form in iron-rich limonite or sandstone. The remnants of these host minerals (called the matrix) are what leave the veins or splotches on the turquoise. (Limonite creates the darks brown markings and the sandstone creates tan markings)
The texture of turquoise is a result of both its structure and composition. If you look at turquoise under a microscope you may see that it is actually an aggregate of microscopic crystals that form a solid mass. The closer the crystals are packed, the finer the texture and the less porous the material. Fine textured turquoise has a shiny waxy luster when it is polished, while less dense turquoise results in a duller luster.

Turquoise from Bisbee Arizona

Turquoise from Bisbee Arizona

The porosity also affects the stones' durability with the less porous turquoise possessing less toughness. Because of the decreased visual appeal and the lesser amount of durability more porous turquoise is often treated to make it smoother, shinier, and more marketable.

turquoise

                                                                                                                                                                                  Most people will be familiar with vein like black matrix running through the vibrant blues or greens; however, the most expensive and prized turquoise has no matrix showing. The second most valuable is a thin web like matrix that is evenly distributed throughout the stone.This really is personal preference, and some turquoise lovers may find imperfections part of the charm.

Turquoise is very soft, ranking a 5-6 on the Mohs hardness scale. This makes the stone ideal for carving and artists throughout history in Europe, Asia, the Middle East and  the Americas have utilized it as a medium for both jewelry and art objects.

Turquoise has a long and varied history (that continues to this day) of being used as talismans, amulets, or religious artifacts as it has been attributed to have special power and meaning to various cultures. The ancient Egyptians, Meso-Americans, Native Americans and Tibetans have believed in the special powers of turquoise for centuries. Some believed that turquoise can protect its wearer from harm, others thought that it brought good luck or longevity, and some uses and meaning have been lost to history.

                  Egyptian middle Kingdom faiance hippo                                        The MET Museum

                  Egyptian middle Kingdom faiance hippo
                                       The MET Museum

The high value placed on fine turquoise caused many imitations to be made. The first of which dates back to ancient Egypt: a glazed earthenware material called faience. Later glass, and enamel were used. In modern times plastic, porcelain, composites of minerals were used. In 1972 the closest “synthetic” turquoise was produced by Pierre Gilson. I put synthetic in quotes since it is actually called a simulant owing to its chemical composition differing from actual turquoise due to a bonding agent. The simulated turquoise is available in both fine and spiderwebbed varieties.

The most common natural stone imitators of turquoise that might be encountered are dyed howlite and magnesite. These stones are both white in their natural state and contain black veining.

All of these imitators are fairly easy to identify by a  trained gemologist and many can be identified by the general consumer as well.

Basics:
Chemical Formula: CuAl6(PO4)4(OH)8•4H2O Copper containing basic aluminium phosphate
Hardness: 5 to 6 on the Mohs scale
Formation:Turquoise occurs as botyroidal (grape-like) masses or nodules in fissures.
Found in: Currently the finest quality turquoise is found in Northeast Iran. Major turquoise deposits are also found in Afghanistan, Argentina, Australia, Brazil, China, Israel, Mexico, Tanzania and the USA.