Made a wax imprint. The monogram has NS or SN in the centre and it may be flanked by E's. The two possible E's look like a good mirror image, suggesting a pro design. Sealing wax has gone out of fashion at least since the 1950's. The style of the letters looks quite modern to me. You may want to measure the ring's opening and hazard a guess on whether it was for a man, a woman or a child. Metal would be nice to know also.
Peter
