9. Jonker Diamond -World’s Largest Diamonds

The Jonker diamond was found at the Elandsfontein mine in South Africa by Johannes Jacobus Jonker on 17 January 1934. The diamond was 726 carats, which at the time was the fourth largest uncut gem ever found.
Weight726 carats (145.2 g)
Country of originSouth Africa
Mine of originElandsfontein
Discovered17 January 1934
Cut byLazare Kaplan
Original ownerErnest Oppenheimer
Estimated value$2.25M+

Discovery of Jonker Diamond

The diamond was discovered by South African farmer Johannes Jacobus Jonker on 17 January 1934.

The diamond was first purchased by Joseph Bastiaenen, an agent of the Diamond Corporation Ltd, a company owned by Sir Ernest Oppenheimer. In 1935 it was purchased by Harry Winston, a New York diamond dealer, for 150,000 pounds. Harry Winston toured the United States with the diamond that was photographed with a number of stars such as Claudette Colbert and Shirley Temple.

Cut of Jonker Diamond

After contemplating the diamond for almost a year, Winston chose Lazare Kaplan to study the Jonker diamond.

Lazare Kaplan was chosen to cut the diamond into several gemstones. The process of examining the diamond to determine the optimal cuts took place over the course of several months. On 27 April 1936, the first cut was made which cut off a 35-carat section, finally ending with the diamond being cut into 13 pieces. The largest piece produced was the Jonker I, a 142.90 ct D-color flawless diamond which was later re-cut to 125.35 carats.

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