I do not believe it is a wax seal, and this is why. In my searching for a match to your ring, all the wax seals I found had a concave image, therby leaving a 3-d impession in the wax. The image on this ring is obviously 3-d , and would thereby leave a concave impression in the wax. It may still be a signficant find, and I hope for you that it is, but I dont think that the wax seal idea is correct. Best of luck.
MIG