CDG Cheat Sheet 2026

The 30 highest-yield CDG facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which risk is most critical when grading a diamond submitted alongside a GIA grading report? → Assuming the report is authentic without verification
2. How should an CDG professional handle unexpected results that differ from predictions? → Analyze factors, document findings, and adjust the approach based on what was learned
3. Which clarity characteristic type CANNOT be improved through laser drilling? → White feathers or clouds
4. A professional diamond grader should recuse themselves from grading a stone when: → They have a financial interest in the stone's grade outcome
5. What is the chemical composition of diamond? → Pure carbon (C)
6. Per GIA standards, which measurement sequence is recorded first for a round diamond? → Minimum diameter × maximum diameter × depth
7. When evaluating a round brilliant for symmetry, a grader notes that opposite facets are not the same size. What symmetry feature is being described? → Upper and lower half facets of unequal size or shape
8. How should an CDG professional present complex findings to non-experts? → Translate into accessible language, use visuals, and verify understanding
9. What is the specific gravity (SG) range for diamond? → 3.50–3.53
10. Raman spectroscopy is preferred over FTIR for confirming a stone is diamond because it specifically identifies: → The characteristic 1332 cm⁻¹ Raman peak unique to diamond's carbon lattice
11. Which of the following is NOT typically included in a professional diamond grading report? → Retail market value
12. The Kimberley Process Certification Scheme (KPCS) was established primarily to prevent trade in diamonds that finance: → Rebel movements against legitimate governments
13. Why is polishing important after cutting? → It enhances sparkle
14. Which security measure most effectively reduces the risk of internal theft of high-value diamonds in a grading laboratory? → Requiring dual control—two-person verification for high-value stones
15. What is a common shape for polished diamonds? → Round brilliant
16. A diamond exhibits strong blue fluorescence under UV light. How does this typically affect its face-up appearance in daylight? → It may appear whiter or have a milky/hazy look in some cases
17. What risk is associated with exposing a fracture-filled diamond to the intense heat of jewelry repair? → Melting or vaporization of the glass filler, destroying the clarity enhancement
18. A diamond retailer advertises a stone as 'GIA certified.' The correct industry terminology is: → GIA graded, since GIA does not certify diamonds
19. How should CDG professionals stay current with regulatory changes? → Actively monitor updates through professional associations and continuing education
20. What is the primary function of Sarine Technologies' DiaExpert system in a diamond grading workflow? → Automated 4C grading using AI-driven imaging
21. Which spectroscopic technique is primarily used to detect the 415 nm absorption line characteristic of Cape series diamonds? → UV-Vis absorption spectroscopy
22. How should an CDG professional approach a novel situation not covered by standard procedures? → Apply foundational principles, assess risks, consult resources, and document decisions
23. What is the purpose of laser drilling in diamond treatment? → To reach dark inclusions and remove or bleach them
24. Which grading report is widely accepted for diamond certification? → GIA report
25. What does a control chart's 'R-chart' (range chart) measure in a diamond grading context? → The consistency (spread) of grades within subgroups over time
26. A lab implements a policy requiring all stones above 1.00 ct to receive three independent clarity grades. What quality principle does this reflect? → Increased sample size to improve decision confidence on high-stakes items
27. Which process improvement concept is demonstrated when a grading lab restructures its workflow so graders never handle the same stone twice on the same day? → Memory-effect mitigation
28. Which mineral is the hardest known natural material? → Diamond
29. When a grader identifies a 'flash effect' showing orange-to-blue color reversal inside a diamond, this most likely indicates: → Presence of fracture filling treatment
30. Which digital plotting convention is used in most grading software to indicate a feather inclusion located inside the stone? → Black outline symbol