I found this web site while searching for the answer to my mystery stone. Recently, I got this ring on line. The seller was listing it as an agate, but I thought it’s a turquoise, so I bought it.
But now, I’m not sure what this stone is. It looks dark fuzzy grayish blue indoor, but it looks totally different under the sunlight. I can see very tiny spider web under the sun. The third picture, I put this ring next to my other spider web turquoise to show how tiny those blue spots are. If this stone is turquoise, which mine it came from? There’s a N or Z etched on the back of the ring.