Gemology Certification Gemology Gem Identification Techniques 2

Question 1

Which optical phenomenon causes a star-shaped reflection in cabochon-cut gems like star sapphire?

Accepted Answer

Asterism

Answer

Asterism is caused by intersecting needle-like inclusions (usually rutile) that reflect light into a star pattern.

Question 2

A gemologist uses a dichroscope and observes two different colors in a stone. This indicates the stone is:

Accepted Answer

Pleochroic

Answer

Pleochroism is the property of showing different colors when viewed from different crystallographic directions.

Question 3

The Chelsea colour filter was originally developed to distinguish which two stones?

Accepted Answer

Emerald and green glass

Answer

The Chelsea filter was designed to separate natural emeralds (appear red) from green glass and paste imitations (appear green).

Question 4

When a gem shows a specific gravity of 4.00, which of these stones is most likely the candidate?

Accepted Answer

Corundum (4.00)

Answer

Corundum (ruby and sapphire) has a specific gravity of approximately 4.00, making it the correct match.

Question 5

Which inclusion type in a diamond is most useful for confirming natural versus synthetic origin?

Accepted Answer

Metallic flux inclusions

Answer

Metallic flux inclusions are characteristic of flux-grown synthetic diamonds and do not occur in natural diamonds.

Gemology Certification Practice Test