My research shows this stone as bowlinite. It's an incredibly rare & expensive stone, but I haven't been able to find much data on it. If you know anything, feel free to share! Hallmarks: None Size: 7.5 Face Length: 1.65" Weight: 11.83g Condition: Pre-loved condition. Pre-loved condition means there is some light to normal wear. This may include marks, scratches, dirt, discoloration etc. Be sure to check out the photos closely & if you have any questions, please don't hesitate to ask. Regarding sterling silver: I almost always keep the patina natural, but am always happy to shine any purchases before shipment. Please be sure to check out my closet as I have many vintage, Native American, Mexican, Southwest, Boho & other unique treasures & statement pieces! Additional items have FREE SHIPPING, so it’s worth it to create a bundle! (Purse symbol icon with a plus sign). Offers are always considered!