Gemology Certification Gemology Gemstone Grading & Evaluation 2 — Questions and Answers
Question 1: Which grading system uses terms like 'Loupe Clean' and 'Piqué' for clarity grades?
- GIA system
- AGS system
- CIBJO system (Correct answer)
- HRD system
Correct answer: CIBJO system
CIBJO (the World Jewellery Confederation) uses terminology such as Loupe Clean (LC) and Piqué (P1–P3) in its gemstone grading nomenclature.
Question 2: A ruby exhibits strong red fluorescence under long-wave UV. How does this typically affect its value?
- It decreases value due to instability
- It has no impact on value
- It can enhance apparent color and increase value (Correct answer)
- It always lowers value because it indicates fractures
Correct answer: It can enhance apparent color and increase value
Strong red fluorescence in rubies can intensify the perceived red color in daylight, often increasing desirability and market value.
Question 3: When grading a fancy-shape diamond, which proportion is most critical for assessing its length-to-width ratio?
- Table percentage
- Crown angle
- L/W ratio (Correct answer)
- Culet size
Correct answer: L/W ratio
The length-to-width (L/W) ratio determines the visual outline and appeal of fancy-shape diamonds, directly influencing their market desirability.
Question 4: In colored stone grading, 'tone' refers to which quality of color?
- The spectral hue of the gemstone
- The degree of lightness or darkness of the color (Correct answer)
- The evenness of color distribution
- The saturation or intensity of the color
Correct answer: The degree of lightness or darkness of the color
Tone describes how light or dark a color appears, ranging from very light to very dark on a grading scale.
Question 5: Which treatment in emeralds is considered standard trade practice and must still be disclosed?
- Flux healing
- Beryllium diffusion
- Cedar oil or resin filling (Correct answer)
- Heat treatment
Correct answer: Cedar oil or resin filling
Cedar oil and resin filling of surface-reaching fractures is a widely accepted trade practice for emeralds but still requires disclosure due to its impact on durability and value.
Question 6: A gemstone described as 'eye-clean' means it has no inclusions visible:
- Under 10x magnification
- To the naked eye at arm's length (Correct answer)
- Under 60x magnification
- Under fiber-optic light
Correct answer: To the naked eye at arm's length
Eye-clean refers to a stone with no inclusions detectable by the unaided eye when viewed at a normal viewing distance of approximately 25–30 cm.
Question 7: Which of the following best describes the 'brilliance' of a cut gemstone?
- The colored light returned from internal reflections
- The white light returned to the viewer through the crown (Correct answer)
- The scattering of light into spectral colors
- The surface luster of the stone
Correct answer: The white light returned to the viewer through the crown
Brilliance refers to the total white light reflected back to the observer from the interior and exterior surfaces of a faceted gemstone.
Gemology Certification Gemology Gemstone Grading & Evaluation 2
Which grading system uses terms like 'Loupe Clean' and 'Piqué' for clarity grades?