The Basics

Also known as the Tolkowsky ideal cut, the classic round cut is regarded as the ideal shape for maximising the aesthetic brilliance and intensity of the stone. Highly versatile, the round brilliant cut diamond is the most popular of the shapes — representing up to 75% of diamonds sold today.


With 58 facets to its crown, girdle and pavilion — and a ratio that usually falls between 1.00 and 1.02 — this shiny cut makes the best of the rough quality of diamond crystal. It is also the most deeply researched cut in the industry; since at least the early 20th century, professional diamond cutters have applied advanced scientific theories of light reflection and complex mathematical models in an effort to perfect their designs.

To achieve optimum sparkle, a large proportion of the rough stone must be cut off. This expensive process is the main reason for the relatively higher price of the stones.

"When it comes to brilliance, the cut is paramount. This popular round cut usually makes for the most eye-catching stones, but you can expect to pay more than other shapes (on a per carat basis) for the quality."

Michael Isaac - Head Gemologist

Historical Background

Although developed in Europe in the middle of the 17th century, the round cut is sometimes referred to as the American Ideal Cut.

The first round of brilliant cuts were called Mazarins, after their designer Cardinal Mazarin, who presented the breakthrough cross-cut diamond in the mid-1600s.

Mazarin’s design underwent a lengthy process of improvement through the 18th century, eventually resulting in the Portuguese Peruzzi, which is alternatively known as the ‘old mine’ or ‘old European cut.’

However, it wasn’t until 1919 that the early modern round brilliant was developed. It became known as the Tolkowsky after its inventor, Belgian engineer Dr. Marcel Tolkowsky, who came from a long line of Polish-Jewish diamond cutters.

In fact, Tolkowsky’s family has continued that tradition, with his cousin Lazare Kaplan and great nephew Gabi Tolkowsky becoming respected diamond cutters in their own right — making them the sixth generation of the family to ply their name in the trade.

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