Lazare Kaplan was a Belgian-born diamond cutter who immigrated to the United States in 1903 and built a reputation over six decades as one of the finest technical cutters in the world. He is credited with developing the modern oval brilliant cut around 1957, applying the brilliant-cut facet arrangement — which had previously been mapped primarily to round stones — to an elongated elliptical outline. The result was a shape that captured nearly all of the light-return performance of a round brilliant while offering more apparent size per carat and a distinctive elongating visual effect on the finger.
Kaplan's most celebrated achievement before the oval was not a cut but a cleaving. In 1914, he was entrusted with the Jonker diamond — a 726-carat rough of exceptional clarity found in South Africa — and tasked with cleaving it into multiple gem-quality stones. The operation required months of study and preparation; the cleave itself took a single strike. The resulting stones, including the 142-carat Jonker I, established Kaplan's reputation as a cutter of the highest order. He later cut several other exceptional stones and was awarded the United States Medal of Freedom in 1970.
The bow-tie is the oval cut's unavoidable characteristic. Every oval brilliant exhibits some degree of bow-tie shadow — a dark, butterfly-shaped zone across the center of the stone that appears when light strikes the elongated pavilion facets at angles that fall below the critical angle for total internal reflection. The question is never whether a bow-tie exists but how severe it is. A subtle bow-tie adds visual interest and depth; a severe one is a visible dark patch that dominates the center of the stone.
Bow-tie severity cannot be determined from a grading report. GIA does not assess or grade it. The only reliable way to evaluate it is to examine the stone — in person, under the diffuse overhead lighting typical of a room rather than the directional spotlight of a display case, which conceals the effect. This is the single most important piece of information for any oval buyer: buy from a vendor who provides video and ideally from whom you can see the stone under realistic conditions.
The oval brilliant Kaplan developed has become, as of the early 2020s, the second-most-popular diamond shape in engagement ring sales — behind only the round brilliant, and ahead of the cushion that held that position for the preceding decade. The oval's appeal is straightforward: it offers brilliant-cut optical performance, visible size advantage per carat (it faces up approximately 10–15% larger than a round of equal weight), and an elongating effect on the finger that many buyers prefer aesthetically.
Lazare Kaplan International, the company that carried his name, went on to become a major force in the American diamond trade and a pioneer in precision-cut certified diamonds through the late 20th century. His name remains associated in the trade with the highest standards of cutting.
Kaplan gave the market a shape that maximized visual size per carat without sacrificing the optical performance of the brilliant cut. Buying an oval well requires evaluating the bow-tie severity — the one quality factor the grading report cannot capture — and understanding that this shape, once the budget's friend, has seen its discount to the round narrow substantially as its popularity has grown.