Hyalite Opal
Among the many different types of opals, hyalite opal is the rarest.
It is classified as a common opal that does not have play-of-color, and its name comes from the Greek word hualos, which means glass. Due to its glass-like transparency, it is also called "glass opal," and because it is extremely difficult to produce, it is also called the mysterious "mysterious stone."
Another mysterious feature is that it fluoresces yellow-green to green when exposed to black light.
Because they are formed drop by drop from small lumps, most of the loose stones are small, less than 1 carat, and larger loose stones like these are even rarer.
Origin: Mexico