CGC Gemstone Grading & Evaluation 2

Question 1

In the GIA colored stone grading system, which three components together describe a gem's color?

Accepted Answer

Hue, tone, and saturation

Answer

GIA describes colored stone color by hue (basic color), tone (lightness/darkness), and saturation (intensity).

Question 2

Which lighting condition is generally recommended when grading the color of colored gemstones?

Accepted Answer

Daylight-equivalent fluorescent light around 5500–6500K

Answer

Daylight-equivalent lighting provides a neutral, consistent standard for color comparison.

Question 3

A grader notes a brownish saturation modifier on a stone. In which hue is a brownish (rather than grayish) modifier expected?

Accepted Answer

Orange spessartine garnet

Answer

Warm hues such as red, orange, and yellow show brownish modifiers, while cool hues show grayish ones.

Question 4

A light, washed-out area in the center of a faceted stone through which you can read print is called what?

Accepted Answer

Windowing

Answer

A window results from a shallow pavilion that lets light pass straight through instead of reflecting back.

Question 5

Dark areas in a face-up colored stone that reduce its brightness are referred to as:

Accepted Answer

Extinction

Answer

Extinction describes dark areas caused by light leaking out or being blocked, often from a deep pavilion.

CGC - Certified Gemstone Consultant Practice Test