Holloway Cut Adviser – The HCA Tool

When choosing a diamond, the informed buyer has a number of tools and reports which can assist them in assessing the quality of the stone before purchase. While some of these tools and programmes can be rather complex and require good research, the Holloway Cut Adviser is a user-friendly analysis tool that can outline details pertaining to the cut quality of the diamond.

What is the Holloway Cut Adviser?

The HCA Tool was developed by Garry Holloway in 2001. The tool uses a small set of data taken from a round brilliant diamond and gives a score from the findings. This score correlates to cut quality, allowing buyers to make an informed estimate about the appearances and quality of the diamond. At the time of its conception, the tool was revolutionary. It drastically cut down the time buyers would spend comparing diamonds by allowing them to input the data and create a shortlist of suitable stones, actively ruling out those with a low score. By today’s standards, the HCA tool is now considered a fairly basic form of analysis, with technological leaps allowing buyers to extract more accurate information before buying a diamond. Nevertheless, the easy to use nature of the tool means it is still considered to be of help in the early stages of choosing a diamond, and a great help to diamond novices looking for a quick answer and simple score regarding cut quality.

The HCA uses five parameters to produce a score. These are: Depth %, Table %, Crown Angle or %, Pavilion Angle or % and finally Culet %. These values will then be run alongside the pre-defined tables that have been assigned by the developer which state the specified criteria for cut quality.

Understanding & Interpreting the HCA Score

The HCA will analyse the data (Depth %, Table % etc) and award the diamond a score from 0-10. The lower the score, the better quality the diamond is considered to be. The creator of the Holloway Cut Adviser tool did not intend for it to be used to make singular decisions based on the purchase of one diamond, rather it should be used to sift through quantities of shortlisted diamonds and rule out those of inferior quality.

A score below two immediately eliminates around 95% of all diamonds; this rules out undesirable cuts, leaving the potential buyer with 5% to assess in more detail. A score between 0-2 is considered a good quality diamond, but still a buyer should consider taking this percentage of the diamonds and placing them under close scrutiny using more refined tools.

Diamonds that score above 5 are to be avoided completely, and a score below 2 and 5 may be considered by those on a tight budget and only if they find a diamond for a good price. It may be possible to find a well-priced diamond with acceptable performance in the 2-5 category, but once again further assessment of the diamond’s properties would be required.

Although they may render a score that deems them ‘good quality’ there are some variances in both score and optical characteristic among diamonds in the 0-2 bracket. The HCA grading system considers these diamonds equally, yet differences in score (such as .5 or 1.5) correlate to trade-offs in some optical characteristics such as brilliance and fire. Ultimately it is up to the buyer to decide which attributes are most important to them when choosing their diamond, and consider the scores and optical variances before making a final decision.

To make this a little clearer, the HCA tool does provide specific grades for the optical properties of Brightness, Scintillation, Fire and Spread. The grades are expressed as Excellent, Very Good, Good, Fair and Poor. These grades are given despite a lack of some specific data pertaining to the diamond (such as facet length and optical symmetry) leading some to question the reliability of the given grade. I would recommend accepting these grades as a guideline, and that assessment of optical properties be given by eye alongside additional lab reports.

As seen above, the HCA also presents a color coded chart, demonstrating exactly where the diamond falls within the proportion charts for a GIA excellent cut grade and an AGS Ideal cut grade. Diamonds giving a score of 0-2 are considered to be in the Ideal cut range and can therefore be categories as Tolkowsky Ideal Cut (TIC), Fiery Ideal Cut (FIC) and Brilliant Ideal Cut (BIC).

Limitation of the HCA Tool

Due to its early conception and subsequent technological advances in diamond analysis, the HCA tool is now considered a rudimental form of diamond quality assessment due to its limitations. These include:

• Measurement of Minor Facets are Not Processed: The Holloway Cut Adviser does not take into consideration the length of the lower girdle or other minor facet lengths. These measurements can affect how the diamond handles light; this information cannot be extracted using the HCA tool.
• Use of Average Values: The results given by the HCA tool are generated by taking average values and proportions from the data. This method does not allow for the slight deviations in the angles that a diamond is cut and instead assumes that it is perfectly symmetrical. A Sarin Report is able to show the deviations between diamond facets.
• Inclusions and Blemishes: The HCA tool cannot account for inclusions and blemishes which can have a huge impact on how effectively the diamond handles light. Fluorescence also cannot be measured using the HCA tool. These limitations lead to a large blind-spot in the analysis of the diamond.

Should I Use the HCA Tool?

The HCA tool will be of great help during the early stages of your diamond search, allowing you to quickly and easily rule out a large percentage of inferior diamonds. However, due to its limitations it is imperative that diamonds scoring 0-2 are subject to further scrutiny. I recommend seeking an ASET image or Idealscope to acquire further information about the cut quality, plus high-res images that show blemishes and inclusions in order to make an informed decision by eye. Read my article on diamond images and video for more details and recommendations.