Holloway Cut Adviser

HCA is a free online cut grading system that I developed based on the Inverse Crown and Pavilion Angle theory . I used our Precious Metals experience with the Ideal-Scope and my Russian research associates software to develop this patent pending system. It receives more than 1,000 hits a day

Holloway Cut Adviser rates a diamond's cut in layman's terms for spread, light return, fire and scintillation. You can use the Holloway Cut Adviser to narrow down your selection. But a diamond can have excellent proportions and poor symmetry, this is immediately apparent with an Ideal-Scope (see here ). The Ideal-Scope will also highlight any bad minor facet proportions.

Below is an example of an HCA result:

Holloway Cut Adviser

Selected:   62% depth, 57% table, 34.5° crown angle, 40.5° pavilion angle. The result is for a symmetrical 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

Even though HCA grades cut more effectively than systems like the AGS , it does not yet factor in symmetry and minor facets. Having found a diamond that scores well, you should employ an expert appraiser to examine the stone. If you decide not to, then at least compare the diamond to others and/or view it through an ideal-scope .
 
A score below 2 (Excellent) means you have eliminated known poor performers (more than 95% of all diamonds). Your own personal preference may be for a diamond with an HCA score of 1.5 more rather than one with a lower score of say 0.5.
 
Many diamonds with excellent scores may not be traditional 'ideal cuts' but we believe their value will rise once the GIA establishes its cut standard.
This system is being continually fine-tuned and results may change without notice.

Garry Holloway FGAA DDT
The red area on this chart represents the lowest HCA scores.
 
Stones near the center of the red region, those with the lowest scores, 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 stones 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 observers head obstructs light sources that would otherwise be returned).
 
Deeper proportioned stones, near the upper part of the red area, have more leakage. Leakage means reduced light return. A limited amount of reduced light return can contribute to a diamonds contrast. Diamonds with a large area of partial leakage table, seen as a pale pink area with an ideal-scope, are best set in open backed rings so light can get in the bottom or pavilion of the diamond. It is possible for light entering the pavilion to leak back out the top as firey dispersed colored flashes. Deeper diamonds that have perfect or hearts and arrows grade symmetry, with scores around 2, will often perform far better than diamonds of lesser symmetry.