CDG Diamond Cutting & Polishing Standards 3

Question 1

When evaluating a round brilliant for symmetry, a grader notes that opposite facets are not the same size. What symmetry feature is being described?

Accepted Answer

Upper and lower half facets of unequal size or shape

Answer

Unequal upper-half or lower-half facets means paired facets on opposite sides of the diamond differ in size or shape, disrupting rotational symmetry.

Question 2

Which term describes the optical phenomenon where a well-cut diamond displays alternating dark and light patterns that create a three-dimensional pinwheel effect?

Accepted Answer

Contrast patterning (Hearts and Arrows effect)

Answer

Contrast patterning—most famously the Hearts and Arrows effect—arises from precise optical symmetry, creating a pinwheel of alternating bright and dark zones visible in a reflector scope.

Question 3

A diamond's 'spread' refers to which measurement characteristic?

Accepted Answer

The face-up diameter relative to the stone's carat weight, indicating how large a diamond appears per carat

Answer

Spread describes how large a diamond looks face-up for its weight; a diamond with good spread appears larger than average for its carat weight.

Question 4

In laser cutting technology used for diamonds, what type of laser is most commonly employed?

Accepted Answer

Nd:YAG (neodymium-doped yttrium aluminum garnet) laser

Answer

Nd:YAG lasers operating in the infrared range are the standard tool for sawing and drilling diamonds because their wavelength is efficiently absorbed by the carbon lattice.

Question 5

Which gemological term describes a cutting style that features concentric rows of rectangular or square facets, with no upper-half or lower-half facets?

Accepted Answer

Step cut

Answer

Step cuts, such as emerald and Asscher cuts, have parallel rows of trapezoidal or rectangular facets arranged in tiers, emphasizing clarity over brilliance.

(CDG) Certified Diamond Grader Practice Test

(CDG) Certified Diamond Grader Practice Test

CDG Diamond Cutting & Polishing Standards 3