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Tanzania's Williamson Mine Yields Another Exceptional 'Bubblegum' Pink Diamond; Petra Sells 32-carat Gem For $15m

Petra Diamonds announced that it sold an exceptional 32.33-carat "bubblegum" pink rough diamond for a remarkable $15 million, or $463,965 per carat. The stone was sourced in Tanzania at Petra's legendary Williamson Mine, which has been producing gem-quality "bubblegum" pink diamonds for the past 76 years.


The diamond was purchased by Golden Yellow Diamonds on behalf of Israeli diamond manufacturer M. A. Anavi Diamond Group, a company specializing in colored diamonds.

As part of the deal, Petra also retained an interest in the diamond once it's polished, so when the faceted gem is sold, Petra will earn 10% of the "value uplift" of that sale, as well.


Petra's most recent find outperformed another notable pink diamond that we wrote about in November 2015. That rough diamond, also from Petra's Williamson Mine and also purchased by Golden Yellow Diamonds on behalf of M. A. Anavi Diamond Group, weighed 23.16 carats and sold for $10.1 million, or $433,938 per carat. At the time, we reported that it was Petra's most significant recovery from the mine to date. Clearly, the 32.33-carat diamond replaces the November discovery as its best find yet.

Vivid pink diamonds of exceptional size and quality are a favorite of gem connoisseurs. In early November, billionaire Joseph Lau purchased a cushion-shaped 16.08-carat pink diamond for $28.5 million ($1.7 million per carat), setting an auction record for any vivid pink diamond.


Although the Williamson Mine has been operational for more than three-quarters of a century and has already generated 20 million carats of diamonds, geologists believe the mine still has the capacity to deliver an additional 40 million carats. The mine’s average depth is only 30 to 35 meters, and theoretically it could continue to yield diamonds as deep as 350 meters.

Pink diamonds owe their bubblegum color to the effects of intense pressure and heat while they were still deep within the earth. These factors caused distortions in the diamond’s crystal lattice that influence the way the diamond absorbs green light, thus reflecting a pink hue.

The Williamson Mine is currently co-owned by Petra Diamonds and the government of Tanzania, which holds a 25% stake.