The DeYoung Red DiamondThe rarest hue in diamond is red, and it is almost unheard of for them to be

The DeYoung Red DiamondThe rarest hue in diamond is red, and it is almost unheard of for them to be graded as such by a laboratory without a colour modifier such as pink or brown (see http://tinyurl.com/la9s9wl). One of the largest in the world is curated in the Smithsonian collection, weighing in at 5.03 carats. To me the hue seems to have a touch of brown modifier, but grading is done under special daylight equivalent lights with the UV component removed to avoid fluorescence affecting the perceived hue (see http://tinyurl.com/kebod3b) while I don’t know in what light the photo was taken.The cause of colour is imperfectly understood, but seems to be defects in the atomic structure caused by slippage within the crystal along cleavage planes in response to tectonic pressures deep within the crust rather than impurities like nitrogen which causes yellow colours. The jeweller who bequeathed it to the museum in 1987 bought it from an estate sale in which it had bee wrongly identified as garnet.LozImage credit: Chip Clarkhttp://geogallery.si.edu/index.php/en/1007278/deyoung-red-diamond -- source link

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