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AN EXTREMELY RARE PURPLISH RED ROUGH DIAMOND

Details
AN EXTREMELY RARE PURPLISH RED ROUGH DIAMOND
Weighing 1.75 carats
With certificate 10155958 dated 1/7/1997 from the Gemological Institute of America stating that the diamond is of natural colour
Sale Room Notice
Please note that the estimate for this purplish red rough diamond has changed. The new estimate is:
SFr. 300,000-450,000
US$ 200,000-300,000

Veuillez noter que l'estimation pour ce diamant brut de couleur "purplish red" a changé. La nouvelle estimation est:
SFr. 300,000-450,000
US$ 200,000-300,000

Lot Essay

Highly saturated diamonds in the red to purple hue range were very rarely encountered prior to the discovery of the Argyle deposits in Australia. Even with that notable discovery only a small number of these strongly coloured diamonds are found, the most significant of which are sold at a tender offering each year.

This 1.75 carat purplish red modified octahedral crystal was observed in GIA GTL several years prior to the discovery of diamonds at the Argyle location. While the source of this stone is unknown, rare diamonds in this hue range have been reported from Brazil, Borneo, India, South Africa, and Venezeula. The cause of colour in such diamonds is not yet thoroughly understood. Although this diamond exhibits an absorption at 415 nanometers due to nitrogen, which confirms that it is a natural diamond, this nitrogen is independent of the cause of the red colour. The heat and pressure applied by the earth at some time after the diamond first crystallizes cause atomic level dislocations, scientifically described as plastic deformation, and associated colour centers. As part of this epigenetic process, the colour centers are trapped along growth or graining planes, forming a distinctly natural pattern of colour zoning. These concentrations of colour, when sufficiently pronounced, impart an overall strong bodycolour to a diamond crystal.

GIA Research
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