CDG Case Analysis & Practical Application 2 — Questions and Answers
Question 1: A diamond has a large feather inclusion that extends from near the girdle toward the center under 10x magnification. What is the primary grading concern with this inclusion?
- It only affects color grade, not clarity
- It poses a durability risk in addition to affecting clarity grade (Correct answer)
- Feathers at the girdle are always graded as external blemishes
- It automatically qualifies the stone as I1 clarity
Correct answer: It poses a durability risk in addition to affecting clarity grade
A feather (fracture) near the girdle creates vulnerability to chipping during setting or wear, making durability a concern alongside the clarity grade.
Question 2: You are grading a diamond initially assessed as VS2. Which scenario would most likely cause you to downgrade it to SI1?
- A single pinpoint visible only at 60x
- A small cloud that is slightly visible under 10x but not eye-visible
- An included crystal that is noticeable under 10x without much searching (Correct answer)
- A surface scratch that can be polished away
Correct answer: An included crystal that is noticeable under 10x without much searching
SI1 clarity means inclusions are noticeable under 10x magnification; an included crystal visible without extensive searching fits SI1 rather than VS2.
Question 3: A diamond shows a heavy concentration of pinpoints (cloud) that reduces transparency and gives the stone a hazy appearance. How should this affect the clarity grade?
- Clouds never affect transparency so the grade is unaffected
- The hazy appearance must be noted and can lower the clarity grade significantly (Correct answer)
- Only clouds visible to the naked eye affect the grade
- The grade is solely determined by the largest single inclusion
Correct answer: The hazy appearance must be noted and can lower the clarity grade significantly
A cloud that affects transparency is a significant clarity characteristic and can substantially lower the grade, especially if it impacts the stone's face-up appearance.
Question 4: When differentiating between a pinpoint and a small crystal under 10x magnification during practical grading, what is the most reliable distinguishing characteristic?
- Pinpoints are always white while crystals are always dark
- Crystals typically have defined reflective faces and three-dimensional form; pinpoints appear as tiny white dots (Correct answer)
- Crystals are only found in the pavilion and pinpoints only in the crown
- Both are identical and the terms are interchangeable in grading reports
Correct answer: Crystals typically have defined reflective faces and three-dimensional form; pinpoints appear as tiny white dots
Crystals have a discernible three-dimensional crystalline form with reflective faces, while pinpoints appear as minute white or dark dots with no defined form.
Question 5: A diamond has a laser drill hole used to remove a dark inclusion. The drill channel is filled with glass. How would a GIA grader treat this on the grading report?
- The diamond is graded as if the original dark inclusion were still present
- Laser drilling is disclosed, and fracture filling is separately disclosed; the filled drill hole lowers the clarity grade further (Correct answer)
- Laser drilling improves clarity grade and no disclosure is needed
- The stone receives an automatic I2 regardless of the original inclusion size
Correct answer: Laser drilling is disclosed, and fracture filling is separately disclosed; the filled drill hole lowers the clarity grade further
GIA discloses both laser drilling and fracture filling separately; a filled laser drill hole is treated as a compound treatment requiring full disclosure on the report.
Question 6: You observe an indented natural at the girdle of a diamond during clarity grading. How is this characteristic correctly classified?
- As a blemish only, since it is on the surface
- As an internal characteristic because it dips below the original polished surface (Correct answer)
- It is ignored entirely as naturals have no impact on clarity grade
- As a polish grade defect, not a clarity characteristic
Correct answer: As an internal characteristic because it dips below the original polished surface
An indented natural dips below the surface plane of the polished diamond, making it an internal characteristic that contributes to the clarity grade.
Question 7: During grading, you observe parallel lines in a diamond that look like growth planes but cause no transparency issues. How do you distinguish surface graining from internal graining?
- Surface graining disappears when you rotate the stone; internal graining does not
- Surface graining is only visible with reflected light on the surface; internal graining is visible with transmitted or dark-field illumination inside the stone (Correct answer)
- They are graded identically and the location does not matter
- Internal graining always creates a milky appearance while surface graining never does
Correct answer: Surface graining is only visible with reflected light on the surface; internal graining is visible with transmitted or dark-field illumination inside the stone
Surface graining is a polish-grade characteristic seen with reflected light at the surface, while internal graining is a clarity characteristic visible within the stone using transmitted or dark-field light.
CDG Case Analysis & Practical Application 2
A diamond has a large feather inclusion that extends from near the girdle toward the center under 10x magnification.
What is the primary grading concern with this inclusion?