White gold diamond and black opal ring Opal: 8mm vertically Ring: Approximately 2-3mm Size 11 3.73g I've occasionally looked at it since I bought it. There are no scratches. K18 stamp There are other stamps as well. I think it's the diamond's carat, but I couldn't tell even with a loupe. It's a very beautiful black opal. The photos were taken indoors at night. It looks even more vivid and beautiful during the day. Thank you.