August 1998

Diamonds:Gemology

The quest for the most beautiful diamond led to development of the Ideal Cut 80 years ago. Now the search is on for even better cuts. To best understand it all, you must first understand "ideal"

The label "ideal" may have something to do with the staying power of the round brilliant cut diamond that Marcel Tolkowsky, of the famed Belgian cutting family, first designed in 1919 with his thesis Diamond Design.

His cut, in essence, was considered "ideal" because of the way it captured diamond's best features: brilliance and dispersion. It was named American Ideal Cut because American cutters were the first to use it (diamond cutting was traditionally done in Europe).

But Tolkowsky wasn't the first to study cut or try to develop a system to classify cuts. In the 1750s, for example, Englishman David Jeffries suggested a system to classify and evaluate diamond cutting. Tolkowsky was likely influenced by Jeffries and also by Henry Morse, a Bostonian who recut old European diamonds to unleash their beauty (in the 1700s and 1800s, diamonds were cut more for weight retention than for maximum return of light and flash of color).

Based on the work of those who had gone before him and on his own genius, Tolkowsky developed proportions for the round brilliant cut that we still call ideal. He suggested the parameters shown on the accompanying illustration for round diamond cutting angles.

Modern Modifications
Variances in today's standards for the Ideal Cut constitute remarkably slight modifications of Tolkowsky's proportions. They include larger tables (to make the diamond look larger) and corresponding changes in crown angles, crown height and pavilion depth.

It's not all about angles. Symmetry and polish are important also. Some diamonds may measure out to Ideal Cut proportions, but still have off-center tables (table closer to the girdle on one side than on the other), misshapen facets, misaligned crown and pavilion facets, out-of-round proportions or overly thick or thin girdles. These all relate to symmetry. Polish characteristics include abrasions, nicks or pits, polishing marks and scratches.

In the next several issues, Professional Jewelerwill consider these and other factors more closely and discuss how individuals and laboratories arrive at cut classifications.

– by Robert Weldon, G.G.

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