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Holloway Cut Adviser (HCA)


Garry Holloway rejects 90% of GIA’s top Cut Quality round diamonds … Why?

90% of GIA XXX grade diamonds are cut to weigh more in Carats and not necessarily cut for light reflection through the stone.

This is where the Holloway Cut Adviser (HCA) tool plays an important step in rejecting those diamonds that have high light leakage and will always look dull (even though they have a GIA XXX grade).

Everyone wants their diamond to look bigger and sparklier!

Holloway Cut Adviser (HCA) rates a diamond’s cut in lay terms for its spread (how big the diamond is for its weight), light return, fire, and scintillation. A diamond with an HCA grade of excellent returns an excellent visual performance.

What this means is the actual diamond cut is good, the reflection of light is excellent and the diamond not only appears larger but also has a strong scintillation.

HCA will help you to quickly reject poorly cut diamonds.


What about the GIA Report?

You must read this! You need to start you research understanding the diamond quality based on Carat Weight, Cut, Clarity and Colour. The GIA report will provide you with an excellent guide on these 4 areas of grading.

But to get a real sparkler! … start the rejecting process with the HCA tool.


Holloway Cut Adviser (HCA)

Holloway Cut Adviser (HCA) is a free online cut grading system developed in 2000 which was granted a US patent in 2007. The Gemmological Institute of America (GIA) developed its cut grading system on the same basis which it began using in 2005.

Below is an example of an HCA result:

Selected: 62% depth, 57% table, 34.5° crown angle, 40.5° pavilion angle. The result is for asymmetrical diamond with a medium girdle and very good polish HCA scores were adjusted Dec. 15, 2001, and Feb. 6, 2003

Factor Grade
Light Return Excellent
Fire Excellent
Scintillation Excellent
Spread or diameter for weight Very Good
Total Visual Performance 0.6 – Excellent
within TIC range


What will HCA NOT do?

HCA does not factor in symmetry, polish, or minor facets. Therefore it is a rejection tool and should be used in conjunction with expert analysis. HCA works very well when combined with an ideal-scope.

HCA does not factor in symmetry, polish or the minor facets.

A score below 2 (Excellent) means you have eliminated known poor performers (NOTE: This accounts for more than 95% of all round diamonds). But a lower score is not the aim; many people prefer diamonds with an HCA score of 1.5 to those below 1.0. The red area on the chart above represents the lowest HCA scores and stones near the center of the red region are often the least affected by small symmetry variations.

A shallower stone, on the lower part of the chart, will look darker when viewed from close up, they are not for everyone.

Shallow-cut diamonds have the advantage of a bigger spread. They are better suited for use as pendants and earring stones where they are not usually viewed from very close proximity, (a close observer’s head obstructs light sources that would otherwise be returned).

Deeper proportioned stones, near the upper part of the red area, have more leakage and reduced light return. Diamonds with a large area of partial leakage table, seen as a pale area with an ideal-scope, are best set in open-backed rings so light can get in the bottom or pavilion of the diamond.

For more information please speak with a Holloways Diamond specialist who will explain the lifetime benefit of an HCA grading.


What does a HCA report look like?

Holloway cut adviser hca diamond proportions calculator tool.