Gemology Certification Gemstone Cutting & Lapidary Arts 2

Question 1

What is the primary purpose of preforming during the gemstone cutting process?

Accepted Answer

Shaping the rough into an approximate final outline before faceting

Answer

Preforming shapes the rough gem into a basic outline (dome, cone, or disc) that closely approximates the finished shape before individual facets are cut.

Question 2

Which lapidary technique is used to create a dome-shaped, unfaceted gemstone surface?

Accepted Answer

Cabochon cutting

Answer

Cabochon cutting grinds and polishes a stone into a smooth, convex dome on top with a flat or slightly curved base, used for opaque or phenomenal gems.

Question 3

What is 'bruting' in diamond cutting?

Accepted Answer

Rounding the diamond's girdle by spinning two diamonds against each other

Answer

Bruting (girdling) creates a round girdle outline by spinning two mounted diamonds against each other on a lathe, shaping the rough into a round profile.

Question 4

When orienting a ruby before cutting, which optical axis direction maximizes the appearance of the red color?

Accepted Answer

Table perpendicular to the c-axis so the c-axis runs through the girdle

Answer

In ruby (trigonal corundum), orienting the table perpendicular to the c-axis makes the red ordinary ray dominate the face-up appearance, intensifying the red color.

Question 5

What grinding medium is most commonly used on a lapidary wheel to shape gemstones harder than quartz?

Accepted Answer

Diamond abrasive

Answer

Diamond abrasive wheels (sintered or electroplated) are used for shaping hard gemstones because diamond is the hardest known natural material at 10 on the Mohs scale.

Gemology Certification Practice Test

Gemology Certification Practice Test

Gemology Certification Gemstone Cutting & Lapidary Arts 2