Cracking the World’s Largest Diamond (Feb, 1938)

Cracking the World’s Largest Diamond

Beauty and brilliance the goal of Jonker craftsmen rather than size—largest of twelve resulting stones weighs 143 carats


PROBABLY one of the most exciting moments in the history of gems was that in which, by a single sharp blow, Lazare Kaplan, diamond expert, clove the great Jonker diamond along the lines he had drawn thereon after months of careful study. Unless his studies had been accurate, the great 726-carat stone might have flown into thousands of worthless fragments. That it did not do so is a testimony to the care and skill and technical knowledge of himself and his son Leo who was his associate in the work.

The largest stone to be cut from the Jonker diamond—which was found by a south African farmer a few years ago, will weigh only 143 carats. Together with eleven others to be cut from the 726-carat original, it weighs but 375 carats. All the rest has been ground to dust in cutting perfect gems. Weight has been sacrificed to color and workmanship. Most big diamonds of history have been cut to preserve weight. Thus it happens that two of the stones in the British crown collection—the Star of Africa and the Cullinan—each weigh more. But the color of the largest cut from the Jonker—called the Jonker Number One—is far superior to either.

Jonker Number One has been insured for $1,000,000. It is owned by a New York jeweler who bought the original rough stone and for whom the Kaplans did the cutting. After the successful cleaving, the resulting stones were further cut and polished for several months, the cutting being done with a phosphor-bronze disc whirling at the rate of 5000 revolutions a minute.

1 comment
  1. Stannous says: September 14, 200710:26 am

    Yesterday it was announced that a 436 carat diamond was found:…
    The 18th largest ever found

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