Dry or wet: how to read an opal photograph

Most opal from Ethiopia changes when it gets wet. A stone photographed as it came from the mine can look very different a week later, dry, on a sorting table. That is why every photograph and video in a Maedot selection says whether the stones were dry or wet.

Where the opal comes from

Buyers usually hear about two areas. Opal from the Menz Gishe district of Shewa, where it occurs as nodules in volcanic rock, was described in Gems & Gemology in 1996. The larger source is Wollo, in the north: a deposit near Wegel Tena was found in 2008 and described in the same journal in 2010.

The Wollo material is mostly white opal, with some brown, fire and colourless crystal opal, often with bright play of colour. The opal lies in a single layer of rock.

Why water matters

Much of this opal is hydrophane, which means it absorbs water. Pieces that look milky or opaque when dry can turn transparent when soaked, and the play of colour can change as well. GIA notes that this behaviour has led to debate about the material's stability and about treatment.

A wet photograph is therefore not a fair picture of the same stone dry, or the other way round. Both are true; they show the material in two different states.

What we do

• Every photograph and video in a selection is unedited and marked dry or wet.
• When material was filmed wet, as it came from the mine, we say so. You can ask to see it dry before you buy.
• If you want a parcel photographed in a particular state or light, ask on the selection page.

Sources

• Johnson et al., “Opal from Shewa Province, Ethiopia”, Gems & Gemology, Summer 1996
• Rondeau et al., “Play-of-Color Opal from Wegel Tena, Wollo Province, Ethiopia”, Gems & Gemology, Summer 2010
• Vertriest et al., “Land of Origins: A Gemological Expedition to Ethiopia”, Gems & Gemology, Spring 2019