CGA CGA Diamond Grading & Gemological Science

Question 1

Which of the four Cs is considered the most important factor in determining a diamond's value?

Accepted Answer

Cut

Answer

Color

Answer

Clarity

Answer

Carat weight

Question 2

On the GIA diamond color scale, which grade represents a colorless diamond?

Accepted Answer

D

Answer

A

Answer

F

Answer

Z

Question 3

A diamond with a 'VS2' clarity grade contains inclusions that are:

Accepted Answer

Very slightly difficult to see under 10x magnification

Answer

Invisible under 10x magnification

Answer

Easily visible to the naked eye

Answer

Visible under 10x magnification but not to the naked eye

Question 4

What is a diamond's 'fluorescence' and how does it typically affect value?

Accepted Answer

Glow under UV light; strong fluorescence often decreases value in colorless diamonds

Answer

Brilliance under natural light; increases value

Answer

Internal reflection pattern; always increases value

Answer

Surface luster; has no effect on value

Question 5

Which diamond cutting style maximizes fire and brilliance through triangular and kite-shaped facets?

Accepted Answer

Brilliant cut

Answer

Rose cut

Answer

Step cut

Answer

Single cut

Question 6

What does the term 'table percentage' refer to in diamond grading?

Accepted Answer

The ratio of the table facet's width to the diamond's overall diameter

Answer

The percentage of the diamond's weight in the table facet

Answer

The depth of the table facet relative to the crown

Answer

The number of facets on the table