Help me with this maker's mak

[makocz]

I found a gold ring that has CB stamped on it, and next to it is "D" in a circle. I thought CB would be Bucherer but I am not sure for the "D" in a circle next to it or is something different completely? I looked few days for any clue, but didn't find anything. Any info would be much appreciate it.

https://www.pricescope.com/community/at ... pg.609352/

ps. I didn't know how to upload a picture, adding link to it.