I purchased this from a very good seller here, but it was a little different from what I imagined, so I am listing it to buy another one (>_<) The claw prongs were more prominent than I expected, so it doesn't seem like I'll be able to wear it daily, which is why I'm listing it. It's a very beautiful opal! It has a unique play-of-color depending on the angle. All photos were taken indoors at night under artificial light. I'm captivated by its mysterious and alluring shine. There are no hallmarks. The size is approximately size 14. Opal Natural stone Colored stone Play-of-color