CGA CGA Colored Gemstones & Pearl Evaluation 3

Question 1

In colored gemstone grading, what does 'saturation' refer to?

Accepted Answer

The intensity or purity of a gemstone's hue

Answer

The transparency of the stone

Answer

The number of facets cut into the stone

Answer

The weight of the stone in carats

Question 2

What is 'heat treatment' in the context of sapphires, and must it be disclosed?

Accepted Answer

A common enhancement that improves color and clarity; must always be disclosed

Answer

A process that adds color to colorless sapphires; never required to disclose

Answer

A surface coating applied to improve luster; optional to disclose

Answer

A treatment that adds asterism; rarely disclosed

Question 3

Which gemstone variety is known as 'trapiche,' featuring a star-like pattern with six spokes?

Accepted Answer

Emerald, ruby, and sapphire can all occur as trapiche varieties

Answer

Star sapphire only

Answer

Only rubies from Thailand

Answer

Only synthetic stones can display this pattern

Question 4

What is the primary purpose of using a Chelsea filter when examining colored gemstones?

Accepted Answer

To help distinguish certain natural gemstones from their synthetic counterparts or common imitations

Answer

To measure the refractive index

Answer

To determine a gemstone's specific gravity

Answer

To examine inclusions under high magnification

Question 5

For a CGA appraisal, what does 'country of origin' determination add to a colored gemstone's value?

Accepted Answer

Prestigious origins like Burmese ruby or Colombian emerald can significantly increase market value

Answer

It has no bearing on value — only quality matters

Answer

It only affects value for diamonds, not colored stones

Answer

Country of origin decreases value due to import restrictions

Question 6

What is a 'doublet' in gemology, and why is it important for CGA appraisers to identify?

Accepted Answer

An assembled stone made of two layers; must be disclosed as it is not a single natural gem

Answer

A pair of matched gemstones; important for pricing sets

Answer

A gemstone with two distinct colors; valuable as a collector's item

Answer

A diamond with two table facets; a cutting error