Hi thanks for writing in. There are some interesting French AC initials in a diamond shape lozenge but as you mention the gold standard is marked 14K and the ring is ca. 1940s -1950s, it won't be French.
Can you provide any more details, and are you able to attach a photo or photos in a follow-up submission, (up to 4 photos can be attached now). Please type "Diamond ring marking | AC in Diamond" in the subject field. Thank you
