How do you describe the crisp green glow of an emerald or the complex interplay between colours in a ruby?
Each gem is unique, so words cannot paint an accurate picture, and digital photographs do not capture their colour accurately. Now a technique to describe and record a jewel鈥檚 exact colour has been developed by Menahem Sevdermish of gem software company GemEwizard, based in Ramat Gan, Israel. The technique should vastly improve the buying and selling of precious stones online, and could also help to spot stolen gems. 鈥淚t鈥檚 like the fingerprint of the stone,鈥� he says.
Diamonds are commonly traded online because their vital characteristics, including tint, clarity, cut and carat value, are easily described. Gems are different, says Richard Drucker, a gemologist in Northbrook, Illinois. 鈥淲e just say 鈥榮lightly purplish, medium tone鈥�. It鈥檚 very vague.鈥�
Advertisement
To record a gem鈥檚 colour, Sevdermish scans it in a white box using special lighting. Computer software then splits the image into thousands of spots, like pixels, and measures the hue, darkness, and colour intensity of each. This numerical description of the gem at each spot forms a unique colour map.
An online seller could scan a gem and email its map to a buyer, who could use Sevdermish鈥檚 database of 150,000 fingerprinted gem images to show the closest match on screen or compare the fingerprint with the details of a lost or stolen jewel.
Sevdermish presented the tool at the Gemological Research Conference in San Diego, California, on 26 August.
