Large crack from left to right.

Back of the stone showing white opal filling the crack.

Detail of the crack cabochon side.

Microscope view (200 x) : the crack is filled with younger opal diffracting red color against green of the opal body.
Little dark inclusions are crystals, perhaps hematite.

Well, this don't say that all cracks in ET opals are naturally repaired. ET opal went on the market 15 years ago, it really reached a noticeable status few years ago. Meaning that our knowledge is still very young. Eyaopal & Opalinda work together for 10 years now, and some informations are relevant.

Et opal is complex, deposits are numerous, recently (re)discovered ... or still unknown. The opals unearthed are wery different in varieties and behaviour. The best known deposit is the Mezezo area one. At least we can distinguish 2 types : hydrophane and the others. The more stable are the hydrophanes but they are often fragile. They display incredible patterns and unbelievable bright colors and in big sizes.They fear water and like dry. Some hydrophane ET opals handle 500°C in the oven without any problem. Smiling with more flashy colors. Few other explode when put in water. After 2 days in the Tucson conditions we always see our collection surprisingly sparkling. The stones just loose moisture drunk in my close to Sainte-Marie home. Well choosen in the rough the hydrophanes give gorgious gems for jewelry.

95% or more of the non hydrophane Mezezo's opals are unstable. Nice it's not 100%. 5% is good enough to work with. In all other deposits around the world, including Lightning Ridge, a carefful selection must be done before cutting. For Mezezo's : the more crystally the more crazing? Perhaps a little law. Again : careffuly choosing the rough, dealing with reliable dealers for cut stones are the ways. Like all other countries opal, any crazing opal should be replaced or payed back by the dealer.
As said, Mezezo is not the only spot. We are very happy with white and crystal ET opal. They do not come in nodules like the Mezezo's. Wonderfull in colors and very hard when cutting. Here we believe that 95% is good for jewelry. We observe stones cut 5 years ago, brought everywere, and still perfect. That's why we are always surprised when visitor says " My gemologist said : never buy Ethiopian opal".

YES, GOOD ETHIOPIAN OPAL EXISTS!

More ...

Precious line in this 10 cm nodule.

The black line is of crystal opal.

Microsope (200 x) shows old displacements and repairs.

Not an harlequin but a nice "old map" pattern. The lighter "drawings" are explained below.

Crystals embeded (perhaps hematite) are visible; or under skin,
or erasered by polishing : lighter "drawings" are here the dark holes.