Australian vs Ethiopian Opal: How They Differ and How to Care for Each

For most of the twentieth century, Australia supplied nearly all the world's precious opal. Then, from around 2008, large deposits in the Wollo region of Ethiopia changed the market. Today Ethiopian opal is the one most buyers in Pakistan see first, often at very friendly prices. Both are real. They are just not the same.

What opal is

Opal is silica with water held inside its structure, usually between 3 and 10 percent. Precious opal is built from tiny spheres of silica stacked in neat rows. Light bends through those rows and splits into colours, the effect called play-of-colour. The size of the spheres decides which colours appear. Larger spheres can show red, which is why red flashes are especially prized.

Australian opal

Australian opal formed in sedimentary rock, in ancient basins where silica-rich water seeped into cracks and cavities.

• Types: black opal, with a dark body that makes colours glow; light or white opal, with a pale body; and boulder opal, which forms in thin seams within ironstone and is often cut with the brown host rock left on the back.
• Stability: most Australian opal is non-hydrophane. It does not soak up water, and stable stones keep their look for decades.
• Doublets and triplets: thin Australian seams are often made into doublets (opal on a dark backing) or triplets (with a clear quartz or glass cap). These are legitimate when disclosed, but they are not solid opal and cost much less.
• Price: solid Australian opal, especially black opal with bright colour, is among the costliest opal per carat.

Ethiopian opal

Ethiopian opal from Wollo formed in volcanic rock, in layers of altered ash.

• Body colour: most is white, cream or crystal, sometimes with a yellowish tone. Darker body colours exist, including chocolate brown. Very dark Ethiopian stones are often smoked or dyed, which is a treatment and should be disclosed.
• Play-of-colour: often very bright, with broad flashes. Some stones show colour from every direction, which gives great value for money.
• Hydrophane: much Wollo opal is hydrophane. It absorbs water. When wet, it can turn more transparent and its play-of-colour may fade. As it dries, usually over hours or days, the look returns.
• Price: generally far lower per carat than solid Australian opal of similar size and brightness.

Side by side

How to tell them apart

Origin is not always obvious to the eye, and some Ethiopian stones look very like Australian light opal. A few clues help:

• A dark body with bright colour, or a brown ironstone back, points to Australia.
• A crystal or milky body with a slightly honeyed tone, and broad, rolling flashes, is typical of Ethiopia.
• A flat dark back with a visible join line means a doublet, not solid black opal.
• A hydrophane stone may briefly stick to a damp fingertip or tongue. Please do not test this on someone else's stone.

For an expensive purchase, a lab can confirm the material and any treatment. Our guide to spotting fakes covers doublets in more detail.

Caring for Australian opal

• Avoid knocks and sudden temperature shocks.
• Solid stones can be wiped with a damp cloth and mild soap, then dried.
• Never soak doublets or triplets. Water can get into the glue layer and cloud it.

Caring for Ethiopian opal

• Keep it away from oils, creams, soaps and coloured liquids. A hydrophane stone can absorb them, and some do not come out.
• If it gets wet and turns clear, do not panic. Let it dry slowly at room temperature. Do not use heat.
• Remove rings before washing hands and wuzu if you want to avoid this cycle.
• Store in a soft pouch, apart from harder stones.

Crazing

Crazing is a network of fine cracks that can appear when an opal loses water too quickly. It can affect opal from any source. Most stones that have already been stable for some months after mining are unlikely to craze in normal wear. Avoid long periods in very hot, very dry places such as a car glovebox in summer.

Which one to choose

If you want a daily piece with bright colour on a modest budget, Ethiopian opal is a lovely choice in a pendant or a bezel ring worn with care. If you want a dark, dramatic stone and a material with a long track record of stability, solid Australian opal costs more and rewards it. Our soft stone care guide has more tips, and our opal collection lists the origin we have for every stone. If you love that glow but want something tougher, see moonstone and labradorite.