Identification – Main Lesson

Unit 4: How to Identify Gems

What’s This All About? 

Become a gem detective! Jake teaches us how scientists figure out what type of gemstone they’re looking at using scientific methods.

Key Takeaways:

• Knowing your gem type helps you understand its value, rarity, and how to properly care for it
• Scientists can now create lab-grown gems that have identical physical and chemical properties to natural ones
• This makes telling natural from synthetic gems very challenging and requires expert knowledge
• Some natural gemstones receive treatments to improve their appearance, color, or clarity
• A major part of a gemologist’s job is detecting these treatments and identifying synthetic stones
• Physical properties include:
  • Hardness (measured on the Mohs scale from 1-10)
  • Specific gravity (how heavy the stone feels for its size)
  • Crystal structure (how atoms are arranged inside the gemstone)
• Optical properties include:
  • Refractive index (how much light bends when entering the stone)
  • Dispersion (how the stone splits white light into rainbow colors – this creates “fire”)
  • Pleochroism (when stones appear to change color from different viewing angles)
• Diamond is the hardest natural material, rating a perfect 10 on the Mohs scale
• Cubic zirconia weighs almost four times more than a diamond of

International Gem Society

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