CDG CDG Diamond Treatments & Enhancements 1 — Questions and Answers
Question 1: What substance is most commonly used in fracture filling of diamonds?
- Lead glass (high lead-content glass) (Correct answer)
- Epoxy resin
- Silicone
- Acrylic
Correct answer: Lead glass (high lead-content glass)
Lead glass is the most common fracture-filling material because its refractive index closely matches that of diamond, making the filled fractures nearly invisible.
Question 2: Which of the following is the most telltale sign of fracture filling when viewed under magnification?
- Rainbow flash effect (iridescent color flash) (Correct answer)
- Increased fluorescence
- Surface graining
- Bearding along the girdle
Correct answer: Rainbow flash effect (iridescent color flash)
The iridescent flash effect — typically orange-pink or blue-purple — at the fracture plane is the most characteristic indicator of fracture filling under magnification.
Question 3: How does fracture filling affect a diamond's apparent clarity grade?
- It can improve the apparent clarity by several grades (Correct answer)
- It has no effect on clarity grade
- It always lowers the clarity grade
- It only affects the color grade
Correct answer: It can improve the apparent clarity by several grades
Fracture filling conceals fractures, potentially making a diamond appear several clarity grades higher than its actual untreated grade.
Question 4: Which organization requires disclosure of fracture filling and will not grade treated diamonds on standard reports?
- GIA (Gemological Institute of America) (Correct answer)
- BBB (Better Business Bureau)
- FTC (Federal Trade Commission) only
- Disclosure is optional per any authority
Correct answer: GIA (Gemological Institute of America)
GIA requires disclosure of fracture filling and will not issue standard grading reports for clarity-enhanced diamonds, as consumer transparency is mandatory.
Question 5: What happens to fracture-filled diamonds when exposed to heat during jewelry repair?
- The filler can melt, boil, or be expelled, damaging the treatment (Correct answer)
- The filler becomes more permanent
- The filler turns the diamond yellow
- Nothing — the filler is fully heat resistant
Correct answer: The filler can melt, boil, or be expelled, damaging the treatment
Heat from soldering or repair can melt or expel the lead-glass filler, permanently damaging the treatment and potentially harming the diamond itself.
Question 6: Fracture filling in diamonds is best detected using which lighting technique?
- Darkfield illumination combined with fiber-optic lighting (Correct answer)
- UV fluorescence alone
- Loupe examination in direct sunlight
- Specific gravity measurement
Correct answer: Darkfield illumination combined with fiber-optic lighting
Darkfield illumination combined with fiber-optic lighting most effectively reveals the flash effect and other indicators of fracture filling.
CDG CDG Diamond Treatments & Enhancements 1
What substance is most commonly used in fracture filling of diamonds?