In short: when it comes to synthetic opal vs natural opal, the key difference is origin. Natural opal forms in the earth over a very long time, while synthetic opal is made in a laboratory — it has a similar structure of microscopic silica spheres and a similar play-of-color. Natural opal captivates with an unpredictable pattern that differs from stone to stone, and it can be very expensive. Synthetic opal has intense, more regular color, costs less and is somewhat less prone to drying out. Both should be told apart from opalite — ordinary glass that merely imitates opal.
Opal is hard to mistake for any other stone. Its greatest asset is play-of-color: flashes of color that shift as the angle of the light changes. That is why it has been one of the most prized gemstones for centuries and why it keeps inspiring jewelry designers. Today you will find natural stones, synthetic stones and imitations on the market. In this guide we explain how they differ, how to tell if an opal is real and which one to choose for your jewelry.
Opal is amorphous, hydrated silica — unlike quartz or sapphire, it does not form crystals. It usually contains anywhere from a few percent to more than ten percent water, and it rates 5.5–6.5 on the Mohs hardness scale. That makes it harder than calcite or fluorite but noticeably softer than quartz, so it scratches more easily. The name is traced to the Greek word opallios, meaning “to see a change of color.”
Precious opal is made up of microscopic silica spheres arranged in a regular grid. Light diffracts off them and splits into the colors of the rainbow — an optical effect known as play-of-color. The size of the spheres determines which colors you see: smaller ones produce blues and greens, larger ones oranges and reds. Opalescence, by contrast, is the milky, pearly glow you can see even in stones without any flashes of color.
Most of these stones come from Australia, with other important deposits in Ethiopia and Mexico. Opals with a cat’s-eye effect also occur, though rarely.
Synthetic opal is a stone created by people under laboratory conditions. The process mimics nature: microscopic silica spheres are slowly settled into an ordered structure and then hardened. The first synthetic opals for jewelry were developed in the 1970s by Pierre Gilson, which is why people still talk about “Gilson opals.” Today they are produced in many varieties, sometimes with added resin for extra strength. They are also easy to cut into even cabochons, which makes them well suited to jewelry made in series.
Synthetic opal looks and is structured much like a natural stone, but a few traits set it apart. Its play-of-color is usually vivid and even, and its pattern more orderly. It contains less water, so it is less likely to crack from drying out. It is also far more affordable and comes in many colors, from blue and green to red and white. That makes synthetic opal a great choice for everyday jewelry — a ring, a pendant or a pair of earrings.
| Feature | Natural opal | Synthetic opal |
|---|---|---|
| Origin | Nature; deposits in Australia and elsewhere | Laboratory |
| Play-of-color | Irregular; every stone has its own pattern | Vivid, more regular |
| Water content | Higher; sensitive to drying out | Lower; more stable |
| Cost | Moderate to very high | Much lower |
| Available colors | Depend on the deposit | Wide palette, including rare shades |
| Best for | Collectors, investment pieces | Everyday jewelry and gifts |
Opal guide
Natural vs Synthetic Opal
All opals in the Polcarat Design collection are synthetic.
Below are designs from our workshop — 925 sterling silver, mostly oxidized.
Identifying a genuine opal can be tricky: true play-of-color is hard to fake, but good synthetics come very close to natural stones. A few tips will help you assess a stone:
Tip: the word “opal” alone in a jewelry description is not enough. An honest seller will tell you whether the stone is natural, synthetic or a doublet.
Opalite is not synthetic opal but glass (less often plastic) made to imitate it. It has a milky color with a bluish or pinkish glow, but no true play-of-color — the sheen does not change color as you turn the stone. Opalite often ends up in inexpensive jewelry and is sometimes sold under misleading names.
Opal also should not be confused with moonstone. Moonstone has a bluish, floating glow but shows no flashes of color. An alternative like that can look lovely — as long as it is labeled honestly.
The choice depends on what you expect from the stone. Natural opal is a good pick for collectors and for anyone who values a stone’s story — the pattern of each natural stone is its own, but it is an expensive gem that needs careful handling. Synthetic opal works better in everyday jewelry: its color is vivid, it is more stable and it costs less, so it is easier to put together a matching ring, necklace and earrings from the same series.
In oxidized silver, an opalescent stone is a beautiful fit for vintage-style jewelry, while in bright, polished silver it looks lighter and more modern. Keep in mind that opal is only moderately hard: a ring worn every day is more exposed to knocks than a pendant or earrings.
In our family jewelry workshop in Rumia, Poland, we have been making 925 sterling silver jewelry since 1984 — cast and then hand-finished. We will say it plainly: all the opals in our collection are synthetic. We choose them for their vivid color, which looks beautiful in openwork oxidized settings. You will find them in our 2173, 2171, 2168 and 2115 series (in the 2115 series we call them opalescent crystals). See all the designs in our synthetic opal jewelry category, and read about the superstitions surrounding this stone in our article Is opal bad luck?
Yes — it has a similar structure and genuine play-of-color, but it was formed in a lab rather than in nature. It is not an imitation, unlike opalite, which is glass.
Synthetic opal usually has a very regular pattern of color patches that flash from every angle. Natural opal has an irregular pattern and often inclusions. Only a gemological examination gives you certainty.
Opal, whether natural or synthetic, is silica with play-of-color. Opalite is glass or plastic that merely imitates it: it has a milky glow but no flashes of color.
No. The flashes of color in synthetic opal come from its structure, not from a dye, so they do not fade. It is still worth protecting the stone from knocks, chemicals and scratches.
No. All the opals in our collection are synthetic, set in 925 sterling silver, most often oxidized.
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