Certified Gemologist Mastery: 5 Practice Exams

Master the Certified Gemologist (CG) exam with confidence through this comprehensive course designed for aspiring gemologists and jewelry professionals. Whether you’re preparing for AGS certification or looking to refresh your expertise, this course offers a focused and effective way to test and enhance your knowledge through 5 high-quality practice exams with over 250 conceptual and scenario-based questions.

Each section is carefully aligned with the key topics outlined in the Certified Gemologist syllabus. The questions are modeled to reflect real-world challenges, terminology, and analysis standards followed by professional gemologists.

Syllabus Topics Covered:

1. Diamond Grading

Objective: Demonstrate expertise in diamond analysis using standardized methods (GIA and AGS).
Subtopics Include:

• 4Cs of Diamond Quality:
  • Color grading (D–Z scale)
  • Clarity grading (Inclusions & Blemishes)
  • Cut grading (AGS Ideal vs. GIA Excellent)
  • Carat weight and its impact on value
• AGS Cut Grading System:
  • Performance-based cut evaluation
  • Light performance and proportion analysis
• Diamond Plotting:
  • Creating accurate diamond plots
  • Inclusions identification & positioning
• Fancy-Shaped Diamond Grading:
  • Differences in grading procedures vs. rounds
  • Cut evaluation challenges
• Fluorescence & Treatments:
  • Identification and impact on value

2. Colored Stone Grading

Objective: Evaluate colored stones accurately using color science and grading techniques.
Subtopics Include:

• Color Science & Grading:
  • Hue, tone, saturation (Munsell system)
  • AGS Colored Stone Grading Scales
• Major Gemstone Identification:
  • Ruby, sapphire, emerald
  • Identification and valuation differences
• Gemstone Phenomena:
  • Asterism, chatoyancy, color change, pleochroism
• Gem Enhancements:
  • Heat treatment, fracture filling, diffusion
  • Disclosure requirements

3. Gem Identification

Objective: Use gemological equipment to distinguish natural, synthetic, and imitation stones.
Subtopics Include:

• Instrument Use:
  • Microscope, refractometer, spectroscope
  • Polariscope, dichroscope, UV light
• Synthetic vs. Natural Gems:
  • Growth structures, inclusions, lab markers
• Imitation Stones & Simulants:
  • Glass, CZ, synthetic spinel, etc.
• Gem Treatments Detection:
  • Detection of filled diamonds, dyed stones

4. Appraisal and Valuation Techniques

Objective: Perform accurate appraisals for insurance, estate, and resale purposes.
Subtopics Include:

• Types of Appraisals:
  • Replacement value, fair market value, liquidation
• Valuation Factors:
  • Market conditions, provenance, brand impact
• Appraisal Writing:
  • Format and standards
  • Legal language and professional ethics
• Insurance and Legal Compliance:
  • USPAP guidelines (where applicable)
  • AGS-approved appraisal methodology

5. Ethics & AGS Standards

Objective: Uphold AGS’s strict code of ethics and consumer protection practices.
Subtopics Include:

• AGS Code of Ethics:
  • Honesty, transparency, customer-first philosophy
• Professional Responsibility:
  • Accurate grading and fair representation
• Recertification and Lifelong Learning:
  • Annual exams, continuing education