CDG Study Guide 2026
Everything you need to pass the CDG exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 CDG Exam Format at a Glance
📚 CDG Topics to Study (69)
✍️ Sample CDG Questions & Answers
1. Between which clarity grades is the price difference per grade typically most dramatic?
The FL to IF distinction commands one of the largest per-grade price jumps because flawless diamonds are extremely rare and highly sought after by premium buyers.
2. A diamond tests positive on a standard thermal conductivity tester but displays unusual strain patterns under the microscope. What is the correct risk management response?
Standard testers confirm thermal conductivity but cannot distinguish all synthetics or certain simulants; conflicting evidence requires escalation to definitive spectroscopic analysis.
3. How does KM (Kiduah Meyuchad) drilling differ from traditional laser drilling?
KM drilling creates a surface-reaching fracture that reaches the inclusion without leaving a straight drill hole, making it harder to detect than traditional laser drilling.
4. What substance is most commonly used in fracture filling of diamonds?
Lead glass is the most common fracture-filling material because its refractive index closely matches that of diamond, making the filled fractures nearly invisible.
5. A diamond grader who accepts gifts from clients in exchange for favorable grades is violating which core ethical principle?
Accepting gifts that influence grading outcomes compromises professional independence and objectivity.
6. Which method is commonly used for root cause analysis in CDG quality management?
Structured root cause analysis methods like Five Whys and fishbone diagrams systematically trace problems to their fundamental causes rather than symptoms.