Holloway Cut Adviser or HCA

With my first Ideal-Scope I observed there is an inverse relationship between Crown and Pavilion angles. If a crown angle was one degree steeper than the ideal of 34.5° then the best pavilion angle would be 0.2° less than the ideal of 40.75° (and vice-a-versa). The crown:pavilion inverse relationship is 5:1. Knowing this helped me buy better cut diamonds from the mid 1990’s on RapNet™, the very first online B2B service. As one of Martin Rapaport’s first subscribers outside USA, we have had a good relationship for decades.

In 1998 the GIA published a Brilliance article. Sadly the scientists were all geochemists (doing an optical study??) and they missed the real relevance of their research. When I showed them in 1999 the importance of the inverse relationship they fobbed me off. I sent them the image below of one of their charts with my black lines added proving they had discovered the inverse relationship between crown and pavilion.

So that fired me up and I decided to build a cut grading system. About that time I ‘met’ a lot of other industry Cut Nuts in an online diamond forum, including Sergey Sivovolenko and Yuri Shelementiev from Moscow State Uni who had developed DiamCalc™. Using DiamCalc I built grids of cut grades for a range of proportions and was later granted a US patent. My friend Leonid Charny coded it and we launched the Holloway Cut Adviser (HCA) on Pricescope in 2001. Since then HCA has been used to grade +10 million diamonds worth more than $50 billion dollars.   (U.S. Patent 7,251,619)

It took GIA another 8 years before they launched a round diamond cut grading system which they copied from HCA. They still have not been able to develop cut grading systems for other diamond shapes.