The HCA gives a pass or fail score to diamond brightness potential, based on 5 critical details.
Used to assess: Brightness forecast.
Not useful for: Contrast, dispersion, scintillation or diamond-specific assessment.
Go to: Holloway Cut Adviser (HCA)
Enter the details requested and hit “go”. The HCA creates an imagined "chalk outline" of the diamond's basic external shape and calculates whether its angles are working together in a way that's likely to have strong brightness (light entering the crown will return to the viewer’s eye) or undesirable leakage (light entering the crown is lost through the bottom of the diamond's bottom). The page returns with an estimated Total Visual Performance score as well as well as other generalized estimates.
A Total Visual Performance grade of Excellent. This will be a score between 0.1 and 1.9: Scores under 2 are all considered equally positive, meaning 0.1 is not preferable to 1.9, and vice-versa.
Scores below 2 are indicative of complimentary angle combinations for abundant brightness. Scores higher than 2 indicate geometry where some of the light entering the crown is predicted to exit through the diamond’s bottom (leakage), creating darkness.
The concept is based on geometry, refractive index and physics so it’s reliable. The HCA is excellent for the stated purpose of weeding out round diamonds which will have undesirable leakage.
Remember my Cut Adviser is a rejection tool to weed out potentially poor performing diamonds.