Our captivating One-of-a-Kind rings feature October's mesmerizing birthstone, opal. Opals form when water seeps into silica-rich rock crevices and then slowly evaporates, leaving behind the dazzling colors and patterns they are famous for. *While we list this ring as non-resizable, we may be able to resize it depending on your desired size. Please contact us with your request. Satomi Kawakita, Boulder Opal Ring, Opal Ring, Boulder Opal, Opal Rings, Birthstone, Jewelry Box, Opal, Ring Size