Natural, Synthetic, or Simulant — Know the Difference
Before calling something "fake," it helps to understand the categories of gemstone materials:
- Natural gemstones: Formed by geological processes in the earth, mined and cut. These are the real thing.
- Synthetic (lab-created) gemstones: Chemically and physically identical to natural stones, but grown in a laboratory. Not "fake" — but they should always be disclosed and priced accordingly.
- Simulants (imitations): Materials that look like a gemstone but have different chemical composition. Examples: glass, cubic zirconia (simulating diamond), dyed quartz (simulating emerald).
The real problem isn't synthetics sold as synthetics — it's simulants or synthetics sold as natural gems at inflated prices.
Simple At-Home Tests
While no home test replaces a gemologist's assessment, these checks can raise red flags:
The Fog Test (Diamonds)
Breathe on the stone. A real diamond disperses heat almost instantly, so the fog clears in under a second. Glass and cubic zirconia stay foggy for a few seconds. This test is not definitive alone, but it's a quick indicator.
Temperature Test
Natural gemstones generally feel cool to the touch. Glass warms up quickly in your hand. Hold the stone — a genuine gemstone remains cool for longer. Note: this doesn't work for all stone types.
Magnification Check
Use a loupe (10x magnification) to examine the stone closely:
- Natural stones usually have inclusions — tiny fractures, crystal inclusions, or growth patterns.
- Glass often shows bubbles, swirl patterns, or conchoidal fractures.
- Synthetic stones may show curved growth lines or gas bubbles under magnification.
- A stone that looks too perfect may be lab-grown or glass — genuine natural gems rarely have zero inclusions.
The Scratch Test (Use Carefully)
Harder materials scratch softer ones. A diamond (hardness 10) will scratch glass (hardness ~5.5) easily. However, be cautious — this test can damage stones and settings. Use it only on inconspicuous areas and understand its limitations.
Red Flags When Shopping
- Prices too good to be true: If a "natural ruby" is priced like a piece of glass, it probably is.
- No provenance or certification: Reputable sellers of significant stones provide laboratory certificates.
- Vague descriptions: Terms like "created," "simulated," "cultured," or "color-enhanced" can obscure what you're actually buying.
- Uniform color and no inclusions: Natural gems almost never look absolutely perfect and uniform in color.
- Flimsy settings: Valuable gemstones deserve quality settings. Cheap metal paired with a supposedly precious stone is a warning sign.
Trusted Certifications to Look For
For meaningful purchases, always ask for a certificate from a recognized independent gem laboratory:
| Laboratory | Abbreviation | Known For |
|---|---|---|
| Gemological Institute of America | GIA | Diamonds, colored stones |
| Gübelin Gem Lab | GGL | Colored stones, origin reports |
| Swiss Gemmological Institute | SSEF | Colored stones, pearls |
| American Gem Society | AGS | Diamonds |
| International Gemological Institute | IGI | Diamonds, lab-grown stones |
The Bottom Line
The safest way to buy genuine gemstones is to shop from reputable dealers, ask questions, request certificates for significant purchases, and consider having any important stone independently appraised. Education is your best defense — the more you know, the harder you are to fool.