'Impossibly rare' diamond hogs limelight
A RARE violet diamond, the largest of its kind found at Australia's remote Argyle mine, will be the centrepiece of Rio Tinto's annual pink diamonds showcase, the company said yesterday.
The rough gem, discovered in August last year at a mine where more than 90 per cent of the world's pink and red jewels are produced, originally weighed 9.17 carats and had etchings, pits and crevices.
After weeks of assessment, the Argyle Violet was polished down to a 2.83 carat, oval-shaped diamond.
Rio Tinto Diamonds general manager of sales, Patrick Coppens, said the gem is "impossibly rare".
The company did not put a figure on its worth but said it had been assessed by the Gemological Institute of America as a notable diamond with the colour grade of Fancy Deep Greyish Bluish Violet.
It is not known how diamonds acquire their coloured tinge but it is thought to come from a molecular structure distortion as the jewel forms in the earth's crust or makes its way to the surface.
Diamonds for sale as part of the annual Argyle pink diamonds tender can fetch US$1-2 million (S$1.3-2.7 million) a carat.
Rio Tinto said violet diamonds were extremely rare with only 12 carats of polished stone produced in 32 years.