GIA Diamond Proportions & Cut Analysis

Question 1

What does 'table percentage' refer to in diamond proportions?

Accepted Answer

The ratio of the table facet width to the average girdle diameter

Answer

The ratio of the crown height to the total depth

Answer

The number of facets on the table surface

Answer

The percentage of the diamond's volume above the girdle

Question 2

In a round brilliant diamond, what does the pavilion angle measure?

Accepted Answer

The angle between the pavilion main facets and the girdle plane

Answer

The angle of the crown facets relative to the table

Answer

The angle between the star facets and the table

Answer

The angle of the culet relative to the pavilion base

Question 3

How is 'total depth percentage' calculated in diamond grading?

Accepted Answer

Total depth (table to culet) divided by the average girdle diameter, multiplied by 100

Answer

Pavilion depth divided by crown height, multiplied by 100

Answer

Crown height divided by the average girdle diameter, multiplied by 100

Answer

Total depth divided by the table diameter, multiplied by 100

Question 4

Which table percentage range is generally associated with a GIA Excellent cut grade for a round brilliant diamond?

Accepted Answer

54–57%

Answer

45–52%

Answer

53–58%

Answer

60–65%

Question 5

What does 'girdle thickness' describe in the context of diamond grading?

Accepted Answer

The width of the band separating the crown from the pavilion

Answer

The total weight of the girdle region in carats

Answer

The number of facets polished along the girdle

Answer

The percentage of the diamond's total depth occupied by the girdle

Question 6

What is the 'culet' in diamond anatomy?

Accepted Answer

The small facet or pointed tip at the very bottom of the pavilion

Answer

The large flat facet at the top of the diamond

Answer

A type of clarity inclusion found at the base of the diamond

Answer

The outermost edge of the girdle

Question 7

What are the five cut grades GIA assigns to round brilliant diamonds?

Accepted Answer

Excellent, Very Good, Good, Fair, Poor

Answer

Perfect, Excellent, Very Good, Good, Fair

Answer

Ideal, Premium, Very Good, Good, Poor

Answer

Excellent, Good, Average, Below Average, Poor