CGC CGC Gemstone Treatments & Enhancements 1 — Questions and Answers
Question 1: What is the most common treatment applied to blue sapphires to improve their color?
- Fracture filling
- Beryllium diffusion
- Heat treatment (Correct answer)
- Irradiation
Correct answer: Heat treatment
Heat treatment is the most common and widely accepted treatment for sapphires, used to improve color and clarity by dissolving rutile silk and enhancing hue.
Question 2: Which gemstone treatment involves filling surface-reaching fractures with lead glass to improve apparent clarity?
- Heat treatment
- Fracture filling (Correct answer)
- Coating
- Lattice diffusion
Correct answer: Fracture filling
Fracture filling uses lead glass or other materials injected into surface fractures to reduce their visibility and improve a stone's apparent clarity.
Question 3: What disclosure is required by U.S. Federal Trade Commission (FTC) guidelines when selling a treated gemstone?
- No disclosure is required
- Disclosure only if the buyer asks
- Material treatment information must be disclosed prior to sale (Correct answer)
- Disclosure only for treatments applied after purchase
Correct answer: Material treatment information must be disclosed prior to sale
FTC guidelines require that sellers disclose any material treatments that affect value or require special care, so buyers can make informed purchasing decisions.
Question 4: Which organization's laboratory is considered the gold standard for detecting gemstone treatments in the U.S.?
- IGI
- EGL
- GIA (Correct answer)
- HRD
Correct answer: GIA
GIA's laboratory is widely regarded as the gold standard for gemstone treatment detection due to its rigorous research, equipment, and unbiased reporting.
Question 5: What type of treatment is commonly used on emeralds to mask surface fractures and improve clarity?
- Irradiation
- Fracture filling with oil or resin (Correct answer)
- Heat treatment
- Beryllium diffusion
Correct answer: Fracture filling with oil or resin
Emeralds are commonly fracture-filled with cedar oil, synthetic resins, or epoxies to mask surface fractures, a practice so common it is considered standard in the trade.
Question 6: What is 'lattice diffusion' treatment in sapphires involving beryllium?
- A surface coating applied to change color
- A heat process that drives beryllium into the stone to create or intensify color (Correct answer)
- A fracture-filling technique using beryllium compounds
- A method to create asterism in sapphires
Correct answer: A heat process that drives beryllium into the stone to create or intensify color
Beryllium lattice diffusion involves heating sapphires with beryllium present, which diffuses into the crystal lattice to produce or intensify colors, particularly orange and yellow.
CGC CGC Gemstone Treatments & Enhancements 1
What is the most common treatment applied to blue sapphires to improve their color?