Ideal Cut Diamonds

Marcel Tolkowsky is largely credited as the father of the modern round brilliant cut. Round brilliant cut diamonds are the cut of choice for approximately 80% of all diamond engagement rings. Remarkably, Tolkowsky was only 21 years old when he published ‘Diamond Design’ and changed the way in which diamonds were faceted forever.

Prior to Tolkowsky’s work, diamonds were mainly faceted as old European or Transition cuts. These were very much cut according to the rough crystal, and were shaped with the sole objective of maximizing the yield of the stone.

Tolkowsky was a physicist, mathematician and engineer. He set about conducting a mathematical analysis of the optical properties of a diamond, and investigated how he could optimize them.

The three optical properties Tolkowsky strove to maxmise in a diamond were:

  • Brilliance: Brilliance is defined as the brightness resulting from the reflection of light from the diamond.
  • Fire: fire is best described as the breaking up of white light into spectral colours when it passes through the diamond.
  • Scintillation: Scintillation is the light and dark flashes of light when the diamond is viewed in motion.

All of these three optical properties combine in a well-cut diamond to create a truly mesmerizing stone. In 1919, Tolkowsky presented ‘Diamond Design’ as part of his doctoral thesis at the University of London. This work contained a formula for the specific angles and cutting arrangements for the facets of a diamond, in order to promote the maximum amount of light and brilliance. The proposal suggested a round cut boasting 58 facets, which subsequently became known as the ‘Ideal Cut,’ despite this term never being mentioned in Tolkowsky’s work.  

Ideal Cut Diamond

Tolkowsky’s work promoted the following angles and dimensions for a faceted diamond:

 

Ranges for Tolkowsky’s diamond

Crown Angle

34.5°

Crown Height

16.2%

Pavilion Angle

40.75°

Pavilion Depth

43.1%

Table Width

53%

Girdle Thickness

Knife edge

Culet Facet

None to Very Small

 

From 1920 until the 1950s, this ‘Ideal Cut’ became the most popular cut of diamond. Later on in the 20th century, the improved technology of computers allowed scientists to review the dimensions of the brilliant cut diamond. The modern round brilliant cut diamond has marginally different proportions to Tolkowsky’s suggestions. His work really did pave the way for the modern round brilliant cut diamond.

 

Ranges for a well cut modern round brilliant cut diamond

Crown Angle

30-35°

Crown Height

11-16%

Pavilion Angle

41-42°

Pavilion Depth

43-45%

Table Width

54-66%

Girdle Thickness

Thin to Slightly Thick

Culet Facet

None to Very Small

 

Tolkowsky not only left the legacy of the most popular and widely used diamond cut in the world, but he also inspired a whole family of diamantaires. His cousin Lazare Kaplan invented the method of cleaving diamonds and also developed the oval cut diamond. Tolkowsky’s nephew, Gabi Tolkowsky was also a hugely successful diamond cutter, cutting the Centenary and Jubilee diamonds during his work for De Beers.

Contact our team of diamond specialists for more advice on diamond cuts. Buy ideal cut diamond engagement rings and jewellery online with 0% interest free finance and free UK delivery. Call us on 01335 453 453 or email us at sales@britishdiamondcompany.com.