Gemology Certification Gem Treatments & Enhancements 2 — Questions and Answers
Question 1: Which gemological instrument is most effective for detecting fracture-filling treatments in gemstones?
- Refractometer
- Spectroscope
- Chelsea filter
- Microscope (Correct answer)
Correct answer: Microscope
A microscope reveals the diagnostic 'flash effect,' flow structures, and gas bubbles characteristic of fracture-filling materials.
Question 2: The 'flash effect'—an iridescent blue or orange flash visible under magnification—is most diagnostic of which treatment?
- Heat treatment
- Irradiation
- Fracture filling (Correct answer)
- Diffusion treatment
Correct answer: Fracture filling
The flash effect occurs because the filler material has a different refractive index than the host gem, creating interference colors at the filler-stone interface.
Question 3: Which of the following gemstones is NOT typically subjected to heat treatment as a standard trade practice?
- Ruby
- Blue sapphire
- Tanzanite
- Emerald (Correct answer)
Correct answer: Emerald
Emeralds are too fractured and thermally sensitive for heat treatment; they are instead treated with oils and resins.
Question 4: A diamond described as 'laser drilled' has undergone a treatment intended to improve which property?
- Color
- Clarity (Correct answer)
- Cut symmetry
- Fluorescence
Correct answer: Clarity
Laser drilling creates a microscopic channel to reach dark inclusions, which are then bleached or dissolved to improve the diamond's apparent clarity.
Question 5: Under GIA's grading system for colored stones, which disclosure term indicates no evidence of clarity or color treatment was found?
- Minor
- None detected (Correct answer)
- Natural
- Not applicable
Correct answer: None detected
GIA uses 'None detected' to communicate that laboratory testing found no evidence of enhancement, while acknowledging detection limits.
Question 6: What diagnostic feature under the microscope helps gemologists identify heat-treated rubies compared to non-treated ones?
- Intact, unbroken silk (rutile needles) in their original orientation
- Melted, broken, or absent silk (rutile needles) (Correct answer)
- Increased number of fingerprint inclusions
- Presence of flux inclusions
Correct answer: Melted, broken, or absent silk (rutile needles)
Heat treatment at high temperatures dissolves or alters silk (fine rutile needle inclusions), leaving melted, shortened, or absent needles as a diagnostic indicator.
Question 7: Lead glass filling is most strongly associated with improving the appearance of which gemstone?
- Sapphire
- Emerald
- Ruby (Correct answer)
- Tanzanite
Correct answer: Ruby
Lead glass filling is primarily used on heavily included rubies, using a lead-rich glass to fill fractures and dramatically improve clarity appearance.
Gemology Certification Gem Treatments & Enhancements 2
Which gemological instrument is most effective for detecting fracture-filling treatments in gemstones?