HCA & Ideal Scope: Are they helpful tools?

Notwithstanding that this concept was popularized by Garry Holloway, the idea was birthed by a Japanese scientist known as Okuda. In the 1970s, Okuda developed various ways of studying the light performance of diamonds using colored reflectors in magnified scopes. The method was later popularized when Garry Holloway came up with the Ideal-scope.

The Ideal-scope is a simple magnifying tube built with red reflectors. It is designed to create a structured light environment, which is used to determine how a diamond handles light.

To examine the light performance of a diamond, the latter is placed on the Ideal-scope with its girdle aligned with the bottom of the tube. As light enters the crown from above, it is reflected in the observer’s eyes as red. The red light greatly pertains to the diamond’s scintillation. The light that escapes or leaks through the pavilion of the diamond appears white, while the light emanating from the highest angle seems black - the latter being the light blocked by the observer’s head.

The developer of the ideal scope, Garry Holloway FGAA, DipDT, JAA Appraiser, is a renowned geologist turned jeweler. Mr. Holloway founded Melbourne Precious Metals, presently known as Holloway Diamonds. The Diamond Technology graduate from the Gemological Association of Australia continues to lecture on one of his specialties - the Science of Light™ & Diamond Cut.

Before the ideal scope was designed, Professor Okuda’s concept had already led to the developing of another cutting-edge technology: The Fire Scope™. It was a limited distribution desktop device, and the Ideal-scope tube is its small, portable variant.

Besides gauging a diamond’s light-handling properties, the Ideal-scope may also be used to grade optical symmetry. A professional observer can predict the amount of fire and scintillation a diamond has through the tube. The information obtained is useful not only for diamond buyers keen on investing in an optically symmetrical stone but also for diamond polishers who can adjust the disproportional facets and ensure that the stone achieves its ideal optical symmetry.

One of the best things about the ideal scope is that it can be used with a diamond of any shape, clarity, or color

As is clear from these images, the ideal scope can be used to analyze more than just the light performance of a diamond. It can be taken to determine the optical symmetry and the proportions of the stone.

Moreover, the black areas represent the light returned at high angles. As pointed out, these areas appear dark because the observer’s head blocks the light coming into the tube.

The red areas represent the brightest light that returns to the observer’s eyes, while the pink ones represent less intense light.

White or gray areas represent the light that is not returned to the observer’s eyes. Instead, the light leaks through the pavilion of the diamond.

Optically symmetrical diamonds are marked by abundant red light, with a minimum of white or grey. Such diamonds also sport a pattern of symmetrical black arrows that radiate from their centers.

If a diamond is an average cut, it will appear more pinkish in the Ideal-scope and have areas of white and gray leakage.

Light leakage, a sign of disproportionate facets, is more pronounced in poorly-cut diamonds with chaotic patterns.

The appearance of dark hues through the ideal scope may be counter-intuitive. However, the dark color generally creates a pleasant contrast, adding to the overall brilliance of the stone. Contrary to what many diamond shoppers believe, white color in ideal-scope imaging is not a plus for a diamond. Leakage indicates that certain facets of the diamond are not proportionally cushioned, significantly affecting the stone’s light-handling properties.

In terms of proportions, optically symmetrical diamonds feature sharp patterns of arrows that run through the crown. The pattern becomes more chaotic, with a decline in optical symmetry.

The Holloway Cut Adviser (HCA) is an intuitive tool used to analyze the cut of round diamonds. After analyzing the diamonds, the HCA tool renders a score that the user can then interpret to estimate the cut quality of the stone. The main idea behind the development of the HCA was to help consumers determine the fire, brilliance, and scintillation of round diamonds. Hence, unlike the ideal-scope tube, the HCA tool is used almost exclusively for round cut stones.

The HCA is another popular concept by Garry Holloway, who developed the tool in 2001 to help diamond shoppers eliminate as many differentiators as possible to hunker down on their ideal gems.

For the HCA tool to accurately analyze a diamond, it investigates five parameters of the stone - the Depth %, Crown angle or %, Table %, Culet %, and the Pavilion angle or %. The tool analyzes these values independently in a score of between 0 and 10, then establishes how the values influence the overall cut quality of the round diamond.

Diamonds with a score of 0 or thereabout are considered the best cut quality. However, it is almost impossible to come by a diamond with a score of 0; this would mean that the stone has no performance limitations - a feat impossible to achieve considering that the five major parameters used are always conflicting. This explains why most consumers often look for a score between 1 and 2, in which range diamonds are often classified as Fiery Ideal Cut (FIC), Tolkowsky Ideal Cut (TIC), or Brilliant Ideal Cut (BIC).

Mr. Holloway says the HCA should not be used primarily as a diamond selection tool. Instead, the tool should help shoppers to eliminate poor-performing stones. He encourages opting for a score below 2, as that eliminates over 95% of all the world’s diamonds. But if the budget cannot allow it, settle for what is affordable as long as it is closest to 2 on the HCA score.

Holloway further remarks that going for a diamond score above five on the HCA tool is a false economy. It is so because while the stone may come cheap, its poor cut implies that the diamond’s light performance is below average. Therefore, chances are that one may spend more on having the diamond polished further to achieve an ideal brilliance.

The HCA tool does not only analyze the cut quality of round diamonds depending on the five stated parameters, but it also presents individual scores for the diamond’s Fire, Scintillation, Brilliance, and Spread. Each variable is graded in a score chart that includes Poor, Fair, Good, Very Good, and Excellent.

However, issues have always been raised about the HCA’s competency in analyzing these finer aspects of a diamond. For instance, it is unclear how the tool arrives at a diamond’s scintillation without considering factors such as optical symmetry and the lower girdle facet length.

Another serious concern is that the tool analyzes based on basic 2-dimensional data points. The concept appears to disregard that a diamond’s light performance results from how the entire stone’s facets handle light in 3 dimensions. Also, the HCA tool does not account for the facet precision of a diamond. Besides, it rounds up the input measurements for crown and pavilion facets, thus opening room for wide variances in the output scores.

Lastly, the HCA tool does not consider a detailed synthesis of the diamond’s model but only focuses on the outline of the stone.

Generally, the Ideal-scope is more reliable than the HCA tool; the fundamental difference is their accuracy. Though each tool examines specific aspects of a diamond, the goal is to establish the diamond’s overall brilliance and scintillation, primarily using the cut.

The Ideal-scope is more accurate, with minimal error margins. It errs when interpreting the imaging results, meaning they are more due to human oversight.

The most significant drawback of the HCA is that it presents its analysis based on limited parameters. Most of those analyses are arrived at depending on the outline of the diamond as opposed to its model.

Therefore, a diamond that scores poorly in an ideal scope or the HCA tool does not necessarily imply that the stone is poorly cut. It all comes down to one’s tastes and preferences.

Some consumers view Ideal-scope and HCA data as more theoretical than practical, arguing that eye-clean for a diamond to appear is the real deal.

Both the HCA and the ideal scope are cutting-edge tools designed to assist consumers in shopping for diamonds of superior cut. These tools are still instrumental and can complement cut grade systems developed by reputable gemological labs such as the American Gem Society and the Gemological Institute of America. It is acceptable to demand an Ideal-scope image and HCA analysis reports when shopping for a diamond. Still, nothing else should be concerning if any professional gemological lab grades the diamond and there is a certificate to show for it with ideal proportions.