Silica · SiO₂·nH₂O · 5.5 to 6.5

Opal

Opal is silica with water locked inside, built from tiny spheres stacked like oranges in a crate. When the spheres are even, they split light into flashes of colour, called play of colour. It is soft and can crack if it dries out. Lab opal, first made by Pierre Gilson in 1974, grows the same sphere structure; many lab opals contain a little resin.

From the ground to your hand

The same stone at four moments. Tap a photo of a listing to see it on Amazon.

01 In the ground (step 1 of 4)

Precious opal still in its host rock, Coober Pedy, South Australia, the opal capital of the world.

Real specimen. Photo: Dpulitzer, CC BY-SA 3.0.
02 Out of the lab (step 2 of 4)

Gilson lab opal, the first lab opal, here cut as a triplet (a thin layer with a backing and a clear cap).

Amazon listing photo. See it on Amazon
03 Cut (step 3 of 4)

Natural Ethiopian opal . Opal is almost always cut as a smooth dome to show its colour.

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04 Set (step 4 of 4)

A lab-grown white opal teardrop pendant in sterling silver.

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Mineral: Opal (hydrated silica)
Colour from: Light diffracting off tiny silica spheres
Hardness: 5.5 to 6.5, and brittle
Grown in labs since: 1974 (Gilson)
Famous sources: Australia, Ethiopia, Mexico

A polished precious opal from Coober Pedy showing play of colour. Photo: James St. John, CC BY 2.0.

Famous opal in museums

What the finest natural stones look like: real pieces in public collections. The whole gem museum.

Precious opal in its rock: Opal with play of colour still in its host rock, from the Andamooka opal fields of South Australia. — **Precious opal in its rock**Opal with play of colour still in its host rock, from the Andamooka opal fields of South Australia.Photographed in a museum collectionOpal formed when silica-rich water seeped into cracks and slowly dried into stacks of tiny spheres. Their spacing splits light into colours.Photo: James St. John, CC BY 2.0.

**Precious opal in its rock**Opal with play of colour still in its host rock, from the Andamooka opal fields of South Australia.Photographed in a museum collectionOpal formed when silica-rich water seeped into cracks and slowly dried into stacks of tiny spheres. Their spacing splits light into colours.Photo: James St. John, CC BY 2.0.

A Lightning Ridge black opal: A polished black opal from Lightning Ridge, New South Wales, the only major source of black opal. — **A Lightning Ridge black opal**A polished black opal from Lightning Ridge, New South Wales, the only major source of black opal.Cleveland Museum of Natural HistoryThe dark body makes the colours blaze; fine black opal is among the most valuable gems per carat.Photo: James St. John, CC BY 2.0.

**A Lightning Ridge black opal**A polished black opal from Lightning Ridge, New South Wales, the only major source of black opal.Cleveland Museum of Natural HistoryThe dark body makes the colours blaze; fine black opal is among the most valuable gems per carat.Photo: James St. John, CC BY 2.0.

Lalique’s peacock pectoral: A pectoral ornament of gold, enamel, opals and diamonds with peacocks, made by René Lalique. — **Lalique’s peacock pectoral**A pectoral ornament of gold, enamel, opals and diamonds with peacocks, made by René Lalique.Calouste Gulbenkian Museum, LisbonLalique used opals for their shifting colours, which suited peacock feathers perfectly.Photo: Sailko, CC BY 3.0.

Lalique’s eagle and pines choker plaque: A choker plaque of gold, enamel and opals showing an eagle among pine trees, by René Lalique. — **Lalique’s eagle and pines choker plaque**A choker plaque of gold, enamel and opals showing an eagle among pine trees, by René Lalique.Calouste Gulbenkian Museum, LisbonCalouste Gulbenkian bought Lalique’s jewels directly from the artist, and Lisbon now has the world’s finest group of them.Photo: Sailko, CC BY 3.0.

Mined vs lab-grown opal

Mined and lab-grown opal are the same mineral; this is what differs
	Mined	Lab-grown
How it formed	Silica-rich water seeping into cracks and fossils, over millions of years	Silica spheres settled and bonded in a lab, over months
Look	Irregular patches of colour	Often a regular "snakeskin" or columnar pattern
Treatment	Sometimes doublets, triplets or darkened by sugar or smoke	Often contains resin
Price	From a few dollars to thousands a carat (black opal most)	Low
Care	Avoid knocks, heat and sudden dryness	Same

Treatments. Thin slices of opal are often glued to a dark backing (a doublet) or under a clear quartz cap (a triplet) to look brighter and protect them; both must be disclosed. Some Ethiopian opal soaks up water and turns cloudy for a while, which is normal for that type. All gem treatments explained.

Where natural opal comes from

Pins mark mining districts, not exact mines. Drag to move, pinch or scroll to zoom, tap a pin to read about it. Map data © OpenStreetMap contributors.

List of every place on the map (4)

Opal: Coober Pedy, South Australia, Australia. Opal town where many people live underground to escape the heat.
Opal: Lightning Ridge, New South Wales, Australia. Home of black opal, the most valuable kind.
Opal: Wollo (Welo), Ethiopia. Found in 2008; bright, affordable play-of-colour opal.
Opal: Queretaro, Mexico. Orange "fire opal".

How it is cut

Opal is almost always cut as a cabochon, a smooth dome, because facets would cut through the thin colour layer. Cutters follow the colour bar in the rough, so every natural opal is a one-off shape; lab opal can be cut in calibrated sizes. See cuts from easiest to hardest and whether cutting your own is cheaper than buying cut.

What to buy

Checked in stock on October 10, 2026. Photos are the listings' own; prices are rounded.

Our first pick

PEORA lab-grown white opal teardrop pendant, sterling silver

about $50

Lab opal with real play of colour, from a long-running lab-gem brand.

See it on Amazon

Also good

Myhealingworld natural Ethiopian opal cabochons

about $30

Five small natural opals with rainbow fire, ready to set.

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Also good

Barzel created opal stud earrings, 3 pairs

under $20

Black, white and green created opal studs for the price of one pair.

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Your kit for opal

Five tools that let you check what you bought (a loupe, a UV torch, locking tweezers, a gem box and a pocket scale), plus a turntable that spins your stone under the light the way jewellers show one. The full collector's kit.

LookGemOro 10x triplet loupeunder $20

LookDARKBEAM filtered 365 nm UV flashlightabout $10

HandleHonoson locking tweezers, 3 packabout $10

StoreTeensery gem display boxes with clear lids, 10 packabout $9

ShowComXim motorized turntable, adjustable speed and directionabout $15

MeasureGemOro Platinum XP500 pocket scale, 0.01 gabout $40

In short

Opal is silica and water arranged in microscopic spheres that turn light into colour. Natural opal is mined mostly in Australia and Ethiopia; lab opal copies the same structure. Wear it in protective settings, keep it away from heat and knocks, and ask whether a bright, cheap opal is a doublet or triplet.

See our first pick: PEORA lab-grown white opal teardrop pendant, sterling silver

Frequently Asked Questions

Is lab opal real opal?

Lab opal reproduces opal's structure of silica spheres and shows real play of colour. Many lab opals also contain resin. They must be sold as lab-created, created or synthetic.

What is a doublet or triplet opal?

A thin slice of opal glued to a dark backing (doublet), sometimes with a clear quartz dome on top (triplet). It is real opal, but much less of it, so it should cost less than solid opal and must be disclosed.

Can opal get wet?

Solid Australian opal is fine with water. Some Ethiopian opal absorbs water and turns cloudy until it dries, and doublets and triplets should not be soaked because water can weaken the glue.

How can you tell lab opal by eye?

Often by pattern. Gilson-type lab opal is built from the same silica spheres as natural opal, but grown so evenly that its colour often sits in tidy columns or a scaly "lizard skin" mosaic. Natural opal patterns are more random. Some lab opal also contains plastic (polymer), so ask what the material actually is.

Photo credits

opal-coober-pedy-rough.webp: Dpulitzer, CC BY-SA 3.0, via Wikimedia Commons.
opal-coober-pedy-precious.webp: James St. John, CC BY 2.0, via Wikimedia Commons.
Product photos: Amazon listings, via the Amazon Product Advertising (Creators) API.

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