CGA Gemstone Treatments & Enhancements

Question 1

Which treatment is most commonly applied to rubies and sapphires to improve their color and transparency?

Accepted Answer

Heat treatment

Answer

Fracture filling with lead glass

Answer

Beryllium lattice diffusion

Answer

Surface coating

Question 2

Which organization publishes internationally recognized disclosure guidelines for gemstone treatments used by the trade?

Accepted Answer

CIBJO (World Jewellery Confederation)

Answer

GIA (Gemological Institute of America)

Answer

AGS (American Gem Society)

Answer

ASA (American Society of Appraisers)

Question 3

Fracture filling in diamonds to improve apparent clarity is most commonly accomplished using which substance?

Accepted Answer

High-lead-content glass

Answer

Epoxy resin

Answer

Cedar wood oil

Answer

Silicone polymer

Question 4

What does the acronym HPHT stand for in the context of diamond color treatment?

Accepted Answer

High Pressure High Temperature

Answer

High Polish Heat Technology

Answer

Hydrothermal Pressure Heating Technique

Answer

Heat Processing and Hardness Testing

Question 5

Beryllium diffusion treatment became a major trade concern in the early 2000s and is primarily associated with which gemstone?

Accepted Answer

Sapphire

Answer

Emerald

Answer

Ruby

Answer

Alexandrite

Question 6

Which gemstone is most widely treated with oil or resin fracture filling, making undisclosed treatment a common trade concern?

Accepted Answer

Emerald

Answer

Blue sapphire

Answer

Diamond

Answer

Alexandrite

Question 7

Which type of treatment involves exposing a gem to gamma rays, neutron bombardment, or electron beams to permanently change its color?

Accepted Answer

Irradiation

Answer

Diffusion treatment

Answer

Impregnation

Answer

Bleaching