G-Color is not the highest grade, but fourth on the letter rung below the top-grade D-Color diamonds.
An unspecified private buyer acquired The Rock, for which the pre-auction estimate was between 19 million and 30 million francs.
Max Fawcett, head of jewelry at Christie’s Geneva, hailed a successful sale in “uncharted territory” for a stone of its kind.
Also going under the hammer Wednesday was the “Red Cross” diamond, a 205.1-carat fancy yellow stone, which fetched nearly 14.2 million francs, double the pre-sale estimate. The diamond was cut from a rough stone unearthed from South Africa’s Griqualand mines in the early 20th century, and went up for auction for the first time in 1918.
Fawcett testified to a “huge amount of interest” in the Red Cross diamond, saying that an unspecified “7-figure sum” from the proceeds of the sale to an unspecified private buyer would be donated to the international Red Cross Movement, the Geneva-based humanitarian aid group.
