Mined, grown in a lab, or glass playing dress-up. Opal has range.
The word opal on a jewelry tag can mean three different things: a stone mined from the earth, a stone grown in a lab, or glass or plastic made to look like one. All three can be pretty, and an honest seller will tell you which one you're looking at. Here's the difference between natural, synthetic and imitation opal, how to tell them apart and how to care for each.
We have five opal pieces in the shop right now, starting with this teardrop synthetic opal ring for $23.
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What makes an opal flash
Precious opal is built from tiny spheres of silica stacked in an orderly pattern. Light bends as it passes between the spheres and splits into color. That shifting flash of blue, green, pink and gold is called play-of-color, and it is what sets opal apart from every other gem.
Natural opal
Natural opal formed in the earth over millions of years. Australia is the best-known source, and opal is also mined in Ethiopia and Mexico. Because it formed on its own, no two stones are alike. The color sits in uneven patches, and the back of the stone often shows plain, colorless opal or a bit of the rock it grew in.
Doublets and triplets
These are natural opal in thin form. A doublet is a slice of opal glued to a dark backing. A triplet adds a clear domed cap on top. Both are real opal, but only a thin layer of it, so they cost much less than a solid stone. Look at the piece from the side and you'll see a straight line where the layers meet.
Synthetic opal
Synthetic opal, also called lab-created or lab opal, is made by people, not mined. It is built with the same kind of orderly structure as natural opal, which is why it shows true play-of-color. Pierre Gilson brought the first successful synthetic opal to market in 1974, and other makers followed. Many newer lab opals are bonded with resin, which makes them easy to cut into thin pieces for inlay.
Synthetic opal is bright, even in color and affordable. It turns up in jewelry from the 1970s on, especially in rings and inlaid bands.
Imitation opal
An imitation is a different material made to resemble opal. Vintage costume jewelry is full of them.
- Opalite: milky glass with a soft blue and orange glow. It's sold in crystal shops under its own name and carved into beads and charms. Our handmade opalite charm bracelet shows the look: blue against a dark background, peachy gold when the light shines through.
- Foil glass: glass cabochons with bits of colored foil inside or behind them. Our green faux opal filigree brooch is a good example: tilt it and the flecks of green, blue and gold flash like opal, but the color sits in flat, crinkled bits rather than glowing patches.
- Slocum stone: a glass imitation from the 1970s with flashes of color inside.
- Plastic and resin: light in the hand and warm to the touch.
How to tell them apart
- Look at the pattern. Natural opal is irregular and never repeats. Synthetic opal often looks too orderly, and under a magnifier the patches of color can show a scaly texture that collectors call lizard skin.
- Look at the side. In synthetic opal the color often runs in straight columns from top to bottom. In natural opal it sits in uneven bands and patches.
- Look at the back. A layer of plain opal or rock points to natural. A pattern on the back that matches the front exactly points to synthetic.
- Look for layers. A straight glue line means a doublet or a triplet.
- Look for bubbles. Tiny round bubbles and a soft glow with no real flashes point to glass.
- Look for foil. Flat, crinkly flecks of color that look like bits of shiny paper point to foil glass.
- Consider the price. A large stone with bright, even color at a low price is almost always lab-created or imitation.
These are clues, not proof. Natural opal can sometimes show a similar pattern, so when the value matters, ask a gemologist to confirm it.
See it in person: opal in the shop
Two lab-created stones, one natural opal chunk and two imitations. Each one is a single piece, so when it's gone, it's gone.
Is synthetic opal fake?
No. Lab-created opal is a man-made opal, and it is only a problem when it is sold as natural. It gives you the color and flash of opal for a fraction of the price. What matters is that the listing says clearly which one you're buying.
Caring for opal jewelry
- Clean every kind of opal with a soft damp cloth and a little mild soap. Skip ultrasonic cleaners and harsh chemicals.
- Don't soak doublets or triplets. Water can work its way between the layers and turn them cloudy.
- Keep foil glass dry too. Water that gets behind the stone can dull the foil.
- Natural opal holds a little water, so keep it away from high heat and sudden changes in temperature, which can make it crack.
- Opal is softer than most gems. Store it apart from other jewelry, and take opal rings off for rough work.
Opal in the shop
We have two synthetic opal rings in the shop now, a teardrop statement ring and an inlaid band ring, both listed as synthetic. For natural opal, we have an Australian kangaroo stick pin set with a raw opal chunk. For imitation opal, there's a green faux opal glass brooch in antiqued gold-tone filigree and a handmade opalite charm bracelet on gold-tone wire. You can also browse our vintage rings and vintage brooches for more one-of-a-kind pieces. Every piece is the only one we have.
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Vintage rings →All jewelry →Treasures under $10 →
Keep reading: What Is Paste Jewelry? · What Is Aurora Borealis Rhinestone? · How to Date Vintage Costume Jewelry
Do you own a piece of opal jewelry? Do you know if it's natural, lab-made or glass? Tell us where it came from.