CGC CGC Gemstone Treatments & Enhancements

Question 1

What is the most common treatment applied to blue sapphires to improve their color?

Accepted Answer

Heat treatment

Answer

Fracture filling

Answer

Beryllium diffusion

Answer

Irradiation

Question 2

Which gemstone treatment involves filling surface-reaching fractures with lead glass to improve apparent clarity?

Accepted Answer

Fracture filling

Answer

Heat treatment

Answer

Coating

Answer

Lattice diffusion

Question 3

What disclosure is required by U.S. Federal Trade Commission (FTC) guidelines when selling a treated gemstone?

Accepted Answer

Material treatment information must be disclosed prior to sale

Answer

No disclosure is required

Answer

Disclosure only if the buyer asks

Answer

Disclosure only for treatments applied after purchase

Question 4

Which organization's laboratory is considered the gold standard for detecting gemstone treatments in the U.S.?

Accepted Answer

GIA

Answer

IGI

Answer

EGL

Answer

HRD

Question 5

What type of treatment is commonly used on emeralds to mask surface fractures and improve clarity?

Accepted Answer

Fracture filling with oil or resin

Answer

Irradiation

Answer

Heat treatment

Answer

Beryllium diffusion

Question 6

What is 'lattice diffusion' treatment in sapphires involving beryllium?

Accepted Answer

A heat process that drives beryllium into the stone to create or intensify color

Answer

A surface coating applied to change color

Answer

A fracture-filling technique using beryllium compounds

Answer

A method to create asterism in sapphires