Opal had previously been discovered in the Shewa province of Ethiopia prior to 2008, and although that material is beautiful, it is very unstable and the vast majority of it develops cracks and can literally break apart. Great for specimens, bad for jewelry!! This early material gave “African opal” a bad name. The discovery of a new deposit, in the Welo province in the northern part of the country, quickly brought out the naysayers (most of them Australian opal dealers!) who claimed that this new material, too, was not stable. The reality is that at the time, nobody really knew how stable – or not – this material actually was. The story has a happy ending – 11 years into the discovery, this opal, once cut and polished, has turned out to be more stable, as well as more durable, than most Australian opal.
The Ethiopian Welo opal has some very unusual characteristics. Most notable is its hydrophane property, which means it has an ultra low water content and can actually act like a sponge and absorb water – as much as 10% of its weight. Opal has varying degrees of water in it, and traditional belief is that the higher the natural water content, the less stable the opal. When Ethiopian Welo opal is immersed in water, it will soak up the water. As it does so, the opal’s color will first become very vivid, but as the saturation process continues, the opal will become completely transparent and the color disappears. It is bizzare to witness, and had me completely flipped out when I first began cutting this material back in 2009! Alas, all is not lost – this process is reversible! As the opal begins to dry, it will first become very milky and opaque, and over the coming days – and in some cases weeks – it will gradually return to its original body color, color play, and degree of translucency. It is important for jewelry artists who use these opals to educate their customers – Ethiopian opal is a dynamic stone and care should be taken to avoid soaking it in water or other liquids!
This opal presents lots of opportunities for jewelry artists. Although it’s nice to work with a simple, flat-backed cabochon, the nature of this material lends it to be cut into free form shapes, and often odd shaped pieces polished on all sides. Sometimes it’s hard to decide what should be the front and what should be the back! Let the customer and artist have their choice! Some pieces can be set with a simple wrap, others with prongs, and others with bezels. Let the piece tell you how it wants to be set. Ethiopian Welo opal is often translucent, and if a stone is thin, it can be hard to see the color if the stone is set in an open-backed setting. Therefore, for thin stones, I encourage artists to use a black backing to enable the stone to show its true color and brilliance.
Ethiopian Welo opal is here to stay. It has gained popularity because of its beautiful colors, patterns, and cost. Many people who only knew of opal as a milky, dull-colored stone have been amazed at what gem quality opal actually looks like. Gem opal has finally gone mainstream!!