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Dee Atkinson & Harrison

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GIA Certificated Coloured Diamonds to be Auctioned in February Sale


December 10, 2017

Dee Atkinson & Harrisons saleroom manager, Andrew Spicer, was recently called out to see an elderly gentleman in a West Hull village who said that he had some GIA certificated diamonds. Well, Andrew pricked up his ears at this as he knew from his many years working as a regional jewellery valuer and auctioneer for Bonhams that these are the best diamond certificates you can have. When he arrived at the modest bungalow he was very surprised to find twelve fancy coloured diamonds, all with the correct paperwork, including a very rare Argyle pink and a pale blue stone.

Well, Andrew pricked up his ears at this as he knew from his many years working as a regional jewellery valuer and auctioneer for Bonhams that these are the best diamond certificates you can have. When he arrived at the modest bungalow he was very surprised to find twelve fancy coloured diamonds, all with the correct paperwork, including a very rare Argyle pink and a pale blue stone.

We are all aware of how a diamond is valued by the 4 Cs, colour, clarity, carat and cut, a combination of these will give a value to a stone. There are many companies that provide a certificate but the world renowned, and never disputed king of the pile is the Gemmological Institute of America (GIA). Their grading for colourless stones begins with D and IF (internally flawless) working down the scale; when you come to coloured stones the rarest and most valuable are the saturated pinks, blues and greens, but these are very rarely intense colours. Yellows and browns are more common, with the vivid, intense being the most desirable.

Very few people are qualified to grade coloured diamonds compared to colourless stones due to the lack of comparables available and they have to take into account that not all coloured diamonds have the same depth of colour, for example yellow diamonds occur in a wide range of saturations, while blues do not. There are over twenty colour hues that cover the spectrum including bluish-green, reddish-purple and then you can add a modifying colour to end up with a brownish-purple-pink. The saturation of these hues is then described with one of nine descriptors from faint, fancy light, fancy intense to fancy vivid.

Coloured diamonds tend not to be cut in the traditional brilliant cut as this does not enhance the colour, so more use of modified brilliants, pears and ovals is found and clarity is the least important factor in the overall value.

Looking through the collection, Andrew was delighted to find many Intense Yellow stones but the highlights of the collection are a 1.28 ct cut cornered square modified brilliant cut Natural Light Blue stone that is internally flawless, with an auction estimate of £20,000/25,000, a 2.04 ct pear brilliant cut Natural Fancy Brownish Greenish Yellow stone at £15,000/20,000 and a 0.54 ct oval modified brilliant Natural Fancy Pink stone with an estimate of £4,000/5,000.

This stone also has its certificate number laser etched onto the girdle and comes with the ultimate Argyle certificate. The Argyle mine in the East Kimberley region of remote north of Western Australia was opened in 1983 and is due to close in 2020 as the supply has nearly run dry. They produce more than 90 % of the worlds pink and red diamonds and of all of the rough diamonds mined only 5% are of gem quality, of this less than 1% are pinks. It requires 1,000,000 cts of rough pink stones to get 1 ct of polished stone!

The collection will be auctioned in our Fine Art and Antiques auction on the 9th February.

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