Largest Blue HPHT Synthetic Diamond in GIA Lab

A 5.03 ct Fancy Deep blue HPHT synthetic diamond was examined by GIA (left). Faint but sharp color zoning was observed (middle, field of view 4.77 mm) along with small metallic inclusions and a cavity at the girdle (right, field of view 2.19 mm). Photos by Sood (Oil) Judy Chia (left) and Kyaw Soe Moe (center and right)

The largest faceted colorless HPHT-grown synthetic diamond reported to date is a 10.02 ct E-color, VS1-clarity specimen, cut from a 32.26-carat piece of rough, was reported by IGI Hong Kong in 2015. The diamond was grown by NDT, or New Diamond Technology, is one of the founding members of the new International Grown Diamond Association. Recently, large colorless and near-colorless HPHT-grown diamonds by the Russian company have been investigated by GIA laboratories. The sizes ranged up to up to 5.11 ct. In January 2016, GIA’s New York laboratory examined a 5.03 ct fancy-color HPHT-grown type IIb synthetic diamond produced by NDT. this is the largest faceted blue laboratory-grown diamond studied so far. 

The notes from GIA's lab report stated that the 5.03-carat diamond exhibited a number of traits characteristic of diamonds grown using the high-pressure, high-temperature (HPHT) process, including color zoning and a cuboctahedral growth pattern. The stone was graded a VS1, fancy deep blue. 

"This emerald-cut synthetic diamond was color graded as Fancy Deep blue. This is a very attractive color with no other color component, a prized rarity among natural type IIb diamonds (the Blue Moon, for instance, was graded as Fancy Vivid blue). When viewed under a microscope, faint but sharp color zoning could be seen, indicative of the uneven impurity incorporation of HPHT synthetic diamonds. No strain was observed under crossed polarizers, indicating a very low dislocation density, which is also characteristic of HPHT-grown diamonds. It had VS1 clarity, with only very small metallic inclusions and a cavity observed at the girdle. Fluorescence and phosphorescence images collected using a DiamondView instrument revealed the sample’s cuboctahedral growth pattern, another feature of HPHT synthetics. The long-lasting chalky blue phosphorescence was further analyzed using spectroscopy, and the emission was found to originate from two broad bands centered at approximately 500 and 575 nm (figure 2, right). These bands have previously been reported in NDT’s type IIa and IIb HPHT synthetic diamonds (D’Haenens-Johansson et al., 2015). "

The evaluation of a lab-grown blue diamond of this size is considered by the researchers to be so significant that they opted to publish Lab Notes online ahead of the next quarterly edition of Gems & Gemology.  

To read Lab Notes GIA.edu

Sotheby's Breaks Record with 9.75 carat Blue Diamond

                       © Sothebys

On Nov. 20 a 9.75 ct fancy vivid blue pear-shaped diamond hit the auction block at Sotheby's New York. A frenzied 20 minute bidding war between seven people ensued ending with the stone fetching $3.3 million a carat ($32.6 million total), setting a new record for any diamond's per-carat price sold at auction. 
The price tops the 14.82 carat vivid orange sold by Christie's in Geneva which sold at $2.3 million a carat ($35.5 million total). The diamond has also set a record as the most expensive diamond ever, a spot previously held by the Wittlesbach-Gaff  sold in 2008.
The blue has been dubbed "The Zoe" by its current owner, A Hong Kong collector who remains anonymous. 

The Graff Ruby Lead the Sotheby's Geneva Sale

The cushion-shaped ruby weighing 8.62 carats, set between triangular diamond shoulders within a mount decorated throughout with brilliant-cut diamonds, size 59, signed Graff, together with an alternative ring mount, Graff. Photo Courtesy of Sothebys

The November 12th, 2014 Sotheby's Geneva auction was lead by a truly magnificent pigeon-blood colored ruby known as the "Graff Ruby".  The ring was originally sold at auction nine years ago and was purchased by noted jeweller Laurence Graff for a record breaking price. He later named the ruby "The Graff Ruby". 
In Geneva the ring again fetched a record breaking amount (selling for $8,600,410). The ring was part of the Collection of Dimitri Mavrommatis (16 pieces) which also included a rare 27.54 carat step-cut Kashmir sapphire, as well as several pieces by contemporary jewelers, Graff and JAR (who was represented by a pair of superb sapphire, ruby and diamond earrings).

The step-cut sapphire weighing 27.54 carats, set between pear-shaped diamond shoulders, size 53, together with an alternative ring mount, Graff. Photo Courtesy of Sothebys

The "Graff" Ruby information:
The piece was accompanied by Gübelin report stating that the ruby is of Burmese origin, with no indications of heating. The SSEF report together with a letter stating:
"The Graff Ruby...The described gemstones exhibits an impressive weight and purity, combined with a very pleasant shape and cutting style. The faint inclusions found by microscopic inspection represent the hallmarks of the reputed deposit of Mogok in Burma (Myanmar). The stone has been spared to exposure of thermal treatment and its clarity and colour are natural. Its vivid red, poetically referred to as 'pigeon blood' is due to a combination of well balanced trace elements in the stone, typical and characteristic for rubies of the Mogok gemstone tract. Natural Mogok rubies from this size, colour and clarity represent a great rarity and the Graff ruby with its combination of outstanding characteristics is a very exceptional gemstone."