CDG Gemology & Mineralogy Fundamentals 2

Question 1

What is the chemical composition of diamond?

Accepted Answer

Pure carbon (C)

Answer

Diamond is composed entirely of carbon atoms arranged in a cubic crystal lattice structure.

Question 2

Which crystal system does diamond belong to?

Accepted Answer

Cubic (isometric)

Answer

Diamond crystallizes in the cubic (isometric) system, which accounts for its high symmetry and optical isotropy.

Question 3

What is the specific gravity (SG) range for diamond?

Accepted Answer

3.50–3.53

Answer

Diamond has a specific gravity of approximately 3.50–3.53, reflecting its dense carbon atomic packing.

Question 4

Which property best describes diamond's cleavage?

Accepted Answer

Perfect octahedral cleavage in four directions

Answer

Diamond has perfect octahedral cleavage in four directions parallel to the octahedral faces, which jewelers exploit when cleaving rough stones.

Question 5

What type of luminescence does many gem-quality diamonds exhibit under shortwave UV light?

Accepted Answer

Fluorescence, often blue or inert

Answer

Many diamonds fluoresce blue (or are inert) under shortwave UV, though fluorescence is more commonly tested under longwave UV.

(CDG) Certified Diamond Grader Practice Test