CDG Diamond Cutting & Polishing Standards 2

Question 1

What is the purpose of 'bruting' in the diamond cutting process?

Accepted Answer

To shape the diamond into a round outline by grinding two stones against each other

Answer

Bruting (also called girdling) creates the diamond's circular outline by spinning two diamonds against each other to abrade the girdle into shape.

Question 2

A diamond cutter chooses to 'cross' or 'block' facets during the blocking stage. What does blocking produce?

Accepted Answer

The 8 main crown facets and 8 main pavilion facets, plus the table and culet

Answer

Blocking cuts the 17 or 18 primary facets (8 crown mains, 8 pavilion mains, table, and sometimes culet) that form the diamond's basic symmetrical shape.

Question 3

In the GIA grading system, which cut grade requires that all aspects of cut—proportions, symmetry, and polish—meet the most stringent standards?

Accepted Answer

Excellent

Answer

GIA's Excellent cut grade is the highest, awarded only when proportions, symmetry, and polish all fall within the most favorable ranges for light performance.

Question 4

A polished diamond displays a fuzzy or indistinct reflection of the table when viewed face-up. Which polish characteristic is most likely responsible?

Accepted Answer

Burn marks from overheating the polishing wheel

Answer

Burn marks occur when a facet is polished against the grain or with too much heat, creating a hazy, milky surface that blurs reflections.

Question 5

Which proportion is measured as the distance from the culet to the girdle plane, expressed as a percentage of average girdle diameter?

Accepted Answer

Pavilion depth percentage

Answer

Pavilion depth percentage is the vertical distance from the culet to the girdle, divided by the average girdle diameter, and is critical to how light exits through the bottom of the stone.

(CDG) Certified Diamond Grader Practice Test

(CDG) Certified Diamond Grader Practice Test

CDG Diamond Cutting & Polishing Standards 2