Opal. How to protect yourself from counterfeiting?
The Art of Opal Authentication: How to Spot a Simulant
As gemstone manufacturing technology advances, distinguishing a natural, earth-mined opal from a synthetic imitation requires an increasingly discerning eye. While laboratory testing is always the most definitive method, you don't necessarily need a degree in gemology to spot a fake.
Here is a professional guide to the most reliable indicators of a genuine opal:
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The Sunlight Spectrum. When held against direct sunlight, a genuine opal will project a vibrant, kaleidoscopic spectrum of light onto your fingers. Artificial stones typically lack the complex internal silica structure required to produce this dynamic, colorful light scattering.
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Organic Patterns. Nature rarely repeats itself. In an authentic opal, the internal patterns are asymmetrical and organic. If you observe a rigid, repetitive, or overly perfect geometric structure—often referred to in the trade as a "lizard skin" or "chicken wire" pattern—you are likely looking at a synthetic stone.
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Purity and Transparency. Examine the body color and transparency of the gem. Natural opals generally possess a transparent, translucent, or softly milky appearance. In contrast, many synthetic opals rely on a distinctly dark, artificial substrate to artificially enhance their visual "flash."
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The Profile Check (Multilayering). Natural opals are solid throughout. Examine the stone closely from the side profile. If you see perfectly straight seams or distinct layers of different materials glued together, it is not a solid natural stone. It is likely a doublet or triplet—a thin slice of genuine or synthetic opal glued to a dark backing.
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Fluidity of Color (Iridescence). The celebrated "play-of-color" in a natural opal shifts fluidly and organically as the stone moves under a light source. Synthetic opals often exhibit static, sharply defined zones of color that lack the soft, transitional iridescence of the real thing.
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Microscopic Bubbles. Inspect the gemstone with a jeweler's loupe or a strong magnifying glass. The presence of perfectly round gas bubbles is a dead giveaway of a glass or resin imitation, trapped there during the high-heat manufacturing process. A natural stone's structure will be entirely free of these artificial cavities.
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Market Value. While not a physical test, pricing is a strong indicator of authenticity. High-quality natural opals are precious gemstones, and their valuations reflect their rarity. If the price seems too good to be true for a large, intensely fiery stone, it is almost certainly a fake.
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The Adhesion Test. Though highly unconventional, this old-school tactile method is still used by some: if you lightly touch the stone to your tongue and it noticeably sticks, exercise caution. Natural, non-porous opals typically feel smooth and glide away, whereas certain imitations or artificial composites may adhere.
Armed with these insights, you are now much better equipped to evaluate the authenticity of your collection.
Are you ready to put your opals to the test?