CDG CDG Diamond Treatments & Enhancements

Question 1

What substance is most commonly used in fracture filling of diamonds?

Accepted Answer

Lead glass (high lead-content glass)

Answer

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?

Accepted Answer

Rainbow flash effect (iridescent color flash)

Answer

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?

Accepted Answer

It can improve the apparent clarity by several grades

Answer

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?

Accepted Answer

GIA (Gemological Institute of America)

Answer

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?

Accepted Answer

The filler can melt, boil, or be expelled, damaging the treatment

Answer

Heat from soldering or repair can melt or expel the lead-glass filler, permanently damaging the treatment and potentially harming the diamond itself.

(CDG) Certified Diamond Grader Practice Test

(CDG) Certified Diamond Grader Practice Test

CDG CDG Diamond Treatments & Enhancements