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

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

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

Performance-based cut evaluation

Light performance and proportion analysis

Diamond Plotting:

• Creating accurate diamond plots

• Inclusions identification & positioning

Creating accurate diamond plots

Inclusions identification & positioning

Fancy-Shaped Diamond Grading:

• Differences in grading procedures vs. rounds

• Cut evaluation challenges

Differences in grading procedures vs. rounds

Cut evaluation challenges

Fluorescence & Treatments:

• Identification and impact on value

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

Color Science & Grading:

• Hue, tone, saturation (Munsell system)

• AGS Colored Stone Grading Scales

Hue, tone, saturation (Munsell system)

AGS Colored Stone Grading Scales

Major Gemstone Identification:

• Ruby, sapphire, emerald

• Identification and valuation differences

Ruby, sapphire, emerald

Identification and valuation differences

Gemstone Phenomena:

• Asterism, chatoyancy, color change, pleochroism

Asterism, chatoyancy, color change, pleochroism

Gem Enhancements:

• Heat treatment, fracture filling, diffusion

• Disclosure requirements

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

Instrument Use:

• Microscope, refractometer, spectroscope

• Polariscope, dichroscope, UV light

Microscope, refractometer, spectroscope

Polariscope, dichroscope, UV light

Synthetic vs. Natural Gems:

• Growth structures, inclusions, lab markers

Growth structures, inclusions, lab markers

Imitation Stones & Simulants:

• Glass, CZ, synthetic spinel, etc.

Glass, CZ, synthetic spinel, etc.

Gem Treatments Detection:

• Detection of filled diamonds, dyed stones

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

Types of Appraisals:

• Replacement value, fair market value, liquidation

Replacement value, fair market value, liquidation

Valuation Factors:

• Market conditions, provenance, brand impact

Market conditions, provenance, brand impact

Appraisal Writing:

• Format and standards

• Legal language and professional ethics

Format and standards

Legal language and professional ethics

Insurance and Legal Compliance:

• USPAP guidelines (where applicable)

• AGS-approved appraisal methodology

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

AGS Code of Ethics:

• Honesty, transparency, customer-first philosophy

Honesty, transparency, customer-first philosophy

Professional Responsibility:

• Accurate grading and fair representation

Accurate grading and fair representation

Recertification and Lifelong Learning:

• Annual exams, continuing education

Annual exams, continuing education