Tolkowsky Ideal Cut Diamonds

Marcel Tolkowsky, sometimes referred to as ‘the father of the modern round brilliant cut’ was an engineer by education. Diamond cutting had been in Tolkowsky’s family for generations and this early introduction sowed the seeds for the incredible legacy he would leave to the world of diamonds.

During his PHD studies in 1919, Tolkowsky scrutinized the diamond cutting process, most notably constructing a thesis on the ideal proportions for round brilliant diamonds. The work was published in his book Diamond Design and placed focus upon how to achieve the best brilliance and fire in round cut diamonds based on the physics of light and the ideal angles and proportions necessary to make the most beautiful faceted diamonds. The formula was not perfect but his specifications are aligned with a number of related diamond concepts; the American Ideal, the Tolkowsky Cut, the Tolkowsky Brilliant and the American Cut all draw from Tolkowsky’s suggested proportions and serve as a foundation for ideal round brilliant cuts.

It is worth noting that while Tolkowsky is widely credited with formulating the perfect parameters for round cut diamonds, Henry Dutton Morse, an American diamond cutter, had established the ‘ideal’ ranges long before the publication of Diamond Design. More on the fascinating role of American diamond pioneers in Al Gilbertson’s excellent book American Cut: The First 100 Years.

After Tolkowsky released Diamond Design the term ‘round brilliant’ was quickly coined and cemented its place in diamond terminology. Tolkowsky’s specifications noted that 33 crown facets and 25 pavilion facets with perfect proportions were the key to yielding the greatest light return in round cut diamonds. He also specified the angles and depths as follows:

Interpretations of Tolkowsky’s formula were incorrect for the first 80 years of its existence. While it was initially believed these parameters comprised a specific design, engineer and mathematician Bruce Harding brought the truth to light; that Tolkowsky in fact understood that a narrow range of compatible combinations of possible crown and pavilion angles were possible, involving trade-offs of maximum brilliance versus maximum fire.

Tolkowsky never gave specifications for girdle thickness in Diamond Design. Despite mentioning it within the body of the work, historians have surmised that his workings were based on a knife-edge girdle which is no longer considered optimal for round brilliant diamonds due to the increased risk of chipping very thin girdles. Failure to account for girdle thickness also throws off other proportions such as depth and pavilion percentage.

Modern lighting was not factored in by Tolkowsky – his prescriptions worked particularly well for the type of lighting in the late eighteenth and early nineteenth century which featured gas lights and candles, featuring lighting environments where the most direct light entered the diamond from the sides. But with the advent of electric overhead lighting, a feature of our modern world, modifications of his original design have resulted in much brighter diamonds able to capture optimal quantities of light from above the diamond.

Industry tools and technology have advanced greatly in the years since Tolkowsky developed his formula. Experts are now able to go well beyond the Tolkowsky framework for even better diamond performance. Laser diamond cutting, non-contact digital measuring devices, and sophisticated software now provides a new level of precision. Ideal and super-ideal cut diamonds can now be accurately assessed for their light performance using advanced diamond imaging – a crucial factor when buying any diamond – and light performance based cut grading can be done in the laboratory using high power mathematical ray tracing software.

The basic parameters specified by Tolkowsky were two dimensional, somewhat like a simplified silhouette of the diamond. Modern technology has moved diamond cutting and analysis into the 3D realm and now takes into account all 57 facets of the round brilliant cut. The precision placement of all the interacting facets in three dimensions ensures optimal light transfers within the diamond and back to the eye.

Our A CUT ABOVE® diamonds are the perfect example of going beyond Tolkowsky’s findings in order to achieve optimum light performance; the ultimate Super Ideal diamond.

The original Tolkowsky ideal proportions have been refined; A CUT ABOVE® diamonds represent a very narrow subset of the GIA ‘Excellent’ cut grade category, prioritizing exceptional light performance over the commonly favored carat yield. Unlike Tolkowsky’s specifications, A CUT ABOVE® diamonds deliver top performance in the widest range of lighting conditions. You can read the stringent A CUT ABOVE® specifications here.

The legacy of Tolkowsky ideal cut diamonds remains strong, but informed buyers will appreciate the bigger picture of diamond cut quality. Looking beyond a set of proportions and instead building a firm knowledge of diamond cut grading and diamond imaging will ensure a rounded education that will result in finding a beautiful diamond. There is no secret to cutting a super-ideal cut diamond; Tolkowsky was transparent in his workings and that same transparency is the core of the Whiteflash ethos.

For a closer look at the modern super-ideal cut diamond click here. Alternatively, feel free to use our live chat to contact one of our friendly diamond consultants.