This set weighs in at 5.17 grams.
"Welo opal" is named after the Wollo Province of northern Ethiopia, but the names “wollo” and “wello” are also encountered.
Many of the opals mined in Ethiopia are hydrophane opals, particularly from the Welo rocks.
This opal can have vivid play-of-color flashing from a body color of clear, white, yellow, orange, or brown. All types of Opal have a high water content, up to 10% in some stones. So the make-up of these stones is a clear or translucent white hydrated (meaning having absorbed water) silicate mineral. Their internal structure makes them defract light, and the colors in the stone relate to the conditions when they were being formed.
This is for reference: 1 Carat (ct) is equal to 0.2 gram (g).