Yita Ridge (Mezezo) Thundereggs, Shewa Provence (Ethiopian Opal Thundereggs)

A truly extraordinary thunderegg location, unusual in that it is one of the few to be regularly filled with precious gem material (precious opal). They are tiny eggs - generally around 2-3cm, with 4cm being quite large. They do get a bit bigger, but the prices climb fast! The most familiar form is a deep chestnut brown opal filled with fire and sparkle - known as chocolate opal - but this location is actually more varied than that. It produces opal shades ranging as far as pure white, with a gloriously buttery yellow being the second most common colour. All are extremely beautiful. In addition, I managed to trace a few specimens containing agate, which are also rather lovely even though they are probably considered 'rejects' by the opal hunters who tend to work with this.

The problem with this location is that, while encountering them at all is relatively unusual, the vast majority of them are cracked open or fragmentary. Polished halves, by far my preferred form, are really rarely seen. But it turned out that providing the cracked stone was a reasonably complete 'half', I could work them smooth myself. Grind them flat and polish them with successful results. So I embarked on a journey of discovery with these, finding all sorts of things about them that I never knew from the cracked stones alone. Lots of details familiar from thundereggs occur here - central buttons, or atoll formations for example. And also, sometimes the most fascinating details can show up in the opal itself - bands and swirls. Some of them can even change colour very dramatically when wet, before reverting again as they dry. And of course, being hydrophane opals, they can change over time and come with a uniquely tenuous and dynamic feel that you rarely see in other thundereggs. For example, one stone I bought was depicted as containing a deep brown central blob surrounded by bright yellow - but by the time it got to me, the blob had faded entirely as though it was never there, much to my confusion. And on working, I discovered just how crazily it reacted to water. But more about that on the individual stone here.

One final point is that these stones really need to be seen in the flesh. A scanner or camera can catch a lot of the flash and fire, and a video can show it twinkling - but nothing equals turning it over in your hand and seeing what is going on, down into the depths.