CDG Diamond Grading & Evaluation Techniques 3

Question 1

When color grading a diamond, the stone should be placed in which orientation relative to the master comparison stones?

Accepted Answer

Pavilion-up, matching the comparison stone orientation

Answer

Diamonds are graded color with the pavilion facing up (table down) in a folded grading trough, matching the orientation of master comparison stones.

Question 2

What is the purpose of using master comparison stones in color grading?

Accepted Answer

To provide calibrated color benchmarks for comparison

Answer

Master comparison stones are GIA-graded diamonds used as color benchmarks to ensure consistent and accurate color grade assignments.

Question 3

Under which lighting condition should color grading of a diamond be performed for consistency?

Accepted Answer

Fluorescent daylight-equivalent lighting (D65)

Answer

Color grading is performed under controlled daylight-equivalent fluorescent lighting (approximately 6500K color temperature) to prevent distortion of body color.

Question 4

A diamond with a GIA color grade of 'D' is described as:

Accepted Answer

Colorless, the highest color grade

Answer

D is the highest color grade on the GIA scale, representing a perfectly colorless diamond with no detectable hue.

Question 5

Which characteristic most commonly causes a grader to assign a lower (more yellow) color grade to a diamond?

Accepted Answer

Presence of nitrogen atoms in the crystal lattice

Answer

Nitrogen atoms incorporated into the diamond's crystal lattice absorb blue light, causing the stone to appear yellowish, which lowers its color grade.

(CDG) Certified Diamond Grader Practice Test

(CDG) Certified Diamond Grader Practice Test

CDG Diamond Grading & Evaluation Techniques 3