These dainty simple, but timeless, earrings are made of Ethiopian opal and sterling silver. Most opals are sedimentary in nature--that is, they are created from the layers laid down by ancient waterways. Ethiopian opals, however, are hydrophane opals, created as a result of volcanic activity, forming in nodules within the volcanic ash in stratum between rhyolite layers. “Hydrophane" comes from the Greek words meaning "water-loving," and describes how these opals tend to absorb water. Water absorption can alter the appearance of Ethiopian opal, changing the stone from opaque or semi-translucent to highly translucent and almost transparent!