The markings are typically for the type of metal or manufacturer an not the stone, unless it says cz then it is indicating that you do not have a diamond but rather a cubic zirconium. In rare instances the stones carat weight may be listed either ct meaning carat weight for one stone, or tw for total weight of more than 1 stone. If you tell me what the marking says, or looks like then maybe I can help you or you can take it to an appraiser. If it is a symbol and not a series of letters then this is probably the hallmark (manufacturers logo).
Hope this helps, Susu


