GIA Diamond Proportions & Cut Analysis 2

Question 1

What is 'brilliance' in the context of diamond light performance?

Accepted Answer

The white light reflected from the interior and exterior of a diamond

Answer

Brilliance refers to the white light — both internal and external reflections — that returns to the observer's eye from a diamond.

Question 2

Which term describes the dispersion of white light into spectral rainbow colors in a diamond?

Accepted Answer

Fire

Answer

Fire is the term for the dispersion of white light into its spectral colors as it passes through the diamond.

Question 3

How does an excessively deep (steep) pavilion angle affect the light performance of a round brilliant diamond?

Accepted Answer

It causes light to leak through the pavilion sides rather than reflecting back through the crown

Answer

An excessively steep pavilion angle redirects light out through the pavilion sides rather than totally internally reflecting it back through the crown, reducing brilliance.

Question 4

What is the 'fisheye' effect in a diamond?

Accepted Answer

A reflection of the girdle visible through the table caused by a too-shallow pavilion

Answer

The 'fisheye' effect occurs when the pavilion angle is too shallow, causing a ring-shaped reflection of the girdle to appear through the table.

Question 5

What is 'scintillation' in diamond light performance?

Accepted Answer

The pattern of light and dark areas plus flashes of reflected light when the diamond or viewer moves

Answer

Scintillation refers to the dynamic sparkle — the pattern of light and dark areas and the flashes of reflected light — observed when the diamond, observer, or light source moves.

(GIA) Certified Diamonds Gemological Institute of America Practice Test

(GIA) Certified Diamonds Gemological Institute of America Practice Test

GIA Diamond Proportions & Cut Analysis 2