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The 2.83 carat polished oval-shaped diamond, which has been dubbed the Argyle Violet, will be the centrepiece of the annual Argyle Pink Diamonds Tender.
The Argyle Violet was polished in Western Australia by one of Argyle's master polishers, Richard How Kim Kam, from a 9.17 carat rough diamond discovered in 2015.
The diamond has been assessed by the Gemological Institute of America (GIA) as a notable diamond with the colour grade of fancy deep greyish bluish violet.
Argyle Pink Diamonds manager Josephine Johnson said it was exciting to announce the historic diamond ahead of the tender launch.
"This stunning violet diamond will capture the imagination of the world's leading collectors and connoisseurs," she said.
The Argyle mine in WA's Kimberley region is the world's only source of hydrogen-rich violet diamonds.
The violet diamonds are so rare that only 12 carats of polished diamonds have been produced by Argyle for its tender over 32 years.
The mine produces 90% of the world's pink diamonds.
