Lazare Kaplan International (LKI) is a New York-headquartered diamond manufacturer and dealer founded by Lazare Kaplan Sr. (1883-1986) in Antwerp in 1903 and re-established in New York in 1919 after Kaplan emigrated to the United States during the First World War. The firm is among the longest continuously operating diamond houses in the world, and it occupies a distinctive position in the trade for its early adoption of the Tolkowsky ideal-cut standard, its development of branded ideal-cut diamonds, and its century-long presence in the New York and global rough markets.

The founder and the early years

Lazare Kaplan Sr. was born in Bialystok in what was then the Russian Empire (now Poland) and trained as a diamond cutter in Antwerp from the age of eighteen. He established his first independent workshop in Antwerp in 1903 and built a successful business cutting and dealing diamonds in the European market through the years before the First World War. The German occupation of Belgium in 1914 forced the closure of much of the Antwerp trade, and Kaplan emigrated to the United States in 1919 with his wife and son.

Kaplan opened his first New York workshop in 1919, close to the Bowery and within walking distance of the Forty-Seventh Street diamond district that was then taking shape. He built a reputation as one of the most technically demanding cutters in the city and was among the first American workshops to apply Marcel Tolkowsky's 1919 mathematical analysis of round brilliant proportions to commercial production.

The Jonker Diamond and the rise of the firm

The episode that established Lazare Kaplan in the public imagination came in 1936, when Kaplan was selected by Harry Winston to cleave and cut the Jonker Diamond, a 726-carat rough diamond recovered from the Elandsfontein mine in South Africa in 1934 and purchased by Winston for 700,000 dollars. The decision to cleave such an important rough was high risk, and Kaplan spent more than a year studying the stone before making the first cleavage cut on March 8, 1936, in his New York workshop, with Winston and assembled press present.

The cleavage produced twelve major stones, the largest of which (originally the Jonker I, 142.90 carats) became one of the most famous emerald-cut diamonds of the twentieth century and is now in private collection. The episode established Kaplan's reputation as the foremost cleaver and cutter of his generation and brought the firm to international attention.

Mid-century expansion

From the 1940s onward, Lazare Kaplan expanded into rough-diamond purchasing, polishing operations in Puerto Rico (where the firm operated a polishing factory for several decades, taking advantage of US tax incentives for offshore manufacturing), and the development of the branded ideal-cut programme that would become the Lazare Brilliant. The second-generation leadership under Lazare Kaplan Jr. and the third-generation leadership under Maurice Tempelsman (who had married into the family and rose to prominence in the African diamond trade) carried the firm through decades of growth and significant operations across multiple continents.

Tempelsman's role at LKI was, separately, of substantial historical interest. He served as the firm's chief executive for decades, and his independent African business included long-running relationships with the governments of the Belgian Congo and later Zaire, with implications that have been the subject of journalistic and academic investigation.

The Lazare Brilliant and laser inscription

From the 1980s onward, LKI built its consumer-facing brand around the Lazare Brilliant, a branded ideal-cut round diamond cut to proportions tighter than the broader GIA Excellent specification and inscribed on the girdle with the Lazare name and a unique serial number. The laser-inscription practice, which became technically feasible in the 1980s with the development of suitable lasers and inscription techniques, was pioneered at commercial scale by LKI and has since been adopted as a standard practice across the branded-cut market and in laboratory traceability programmes.

Recent corporate history

LKI was a publicly traded company on the NASDAQ for much of the late twentieth and early twenty-first centuries. The firm encountered significant business difficulties in the 2010s and filed for Chapter 11 bankruptcy in 2014, with subsequent corporate restructuring that reduced the firm's scale considerably. The Lazare Brilliant brand has continued to operate, and the firm's polishing and inscription technologies remain in use, although LKI is no longer the dominant rough-diamond purchaser it was at its mid-century peak.

Legacy in the trade

Lazare Kaplan's contribution to the diamond trade rests on three pillars: the introduction of Tolkowsky-based ideal-cut proportions to commercial scale in the early twentieth century, the development of branded ideal-cut diamonds and laser inscription as a consumer-facing programme in the late twentieth century, and the firm's role in some of the most important diamond cleavages of the twentieth century (most notably the Jonker). The Kaplan name remains associated with the highest standards of round brilliant cutting and with a particular tradition of New York diamond manufacturing that runs from the Bowery workshops of the 1920s through the present day.