Holloway Cut Adviser - What You Should Know
“I’m wondering what your take is on the Holloway Cut Adviser. Is the HCA calculator a good way to pick a diamond? My fiancé is intent on finding a diamond that offers the lowest HCA score. I’ve punched in the parameters for several Brian Gavin Signature round diamonds and they seem to score very well. But it also seems to me that proportions are only part of the puzzle. The premise behind this assumption is based upon some of the things I just read in your article Black by Brian Gavin vs Brian Gavin Signature. Honestly, I hadn’t even been aware that there was such a thing as an ASET Scope prior to reading that blog post. At this point, I’m a bit confused as to how to weight the importance of HCA scores vs ASET. Can you provide some insight?”
Is the HCA Diamond Cut Calculator effective?
The Holloway Cut Adviser is a useful tool, but I think that people put too much weight in the results and miss the true intention that it was designed to accomplish. The answers to your concerns about the HCA are provided within the fine print provided at the top of the page:
“The Holloway Cut Adviser ( U.S. Patent 7,251,619 ) estimates a round diamonds appeal based on its potential Light Return, Fire, Scintillation and Spread. HCA gets no info on symmetry, polish and minor facets; use it only to reject likely bad performing diamonds to narrow down your final selection. Ideal-Scope images and independent appraisers can help after that.”
So the basic premise behind the Holloway Cut Adviser is that it is more of a diamond elimination tool, as opposed to being a diamond selection tool. Use it to narrow down the list of diamonds that you might be considering. Then rely upon reflector scope images, such as ASET and Ideal Scope to further narrow down the list of possibilities.
How do Brian Gavin Diamonds score on HCA:
The range of proportions adhered to during the production of all Brian Gavin Signature round diamonds, represents the middle of the spectrum designated for the zero ideal proportions grade. Thus the reality is that our diamonds tend to score quite nicely on the Holloway Cut Adviser. Here are the results for this 1.062 carat, E-color, VS-2 clarity, Black by Brian Gavin diamond:
As you can see, the diamond scores quite nicely at 1.5 which the HCA states is “Excellent, within TIC range” which means that it is within the range determined by Marcel Tolkowksy to produce the highest volume of light return, brilliance and dispersion. TIC = Tolkowsky Ideal Cut.
One thing I did find surprising is the notation (highlighted in yellow) that the parameters for the “HCA scores were adjusted Dec. 15, 2001 and Feb. 6, 2003.” Both the American Gem Society Laboratory (AGSL) and the GIA Gem Trade Laboratory released major updates to their grading platforms in June 2005. These included adjustments to the proportions grading parameters, and there have been substantial advancements in diamond cut quality since that time.
The effect of minor facets on HCA Score:
Recent studies on the effect of the ancillary angles of a round brilliant cut diamond by Brian Gavin, indicate that the minor facets might play a much larger role in light performance than originally understood. Which makes the role of reflector scope images such as ASET, Ideal Scope and Hearts & Arrows scopes even more critical to the selection process.
The Holloway Cut Adviser is certainly a good tool to use in the early stages of diamond shopping, but remember that it is primarily intended as a diamond elimination tool. And the reality is that there isn’t much point in using it with Brian Gavin Signature round diamonds, because it’s only going to confirm what we already know. That our diamonds are cut to proportions that tend to yield the highest volume of light return and sparkle factor. What the HCA deems to be Excellent, but then we take it a step further, perhaps many steps further, by polishing our diamonds to exhibit exceptional optical precision, as demonstrated by the crisp and complete patterns of hearts and arrows.
