Extremely unique vintage sterling silver 14k sponge coral hessonite garnet ring

Extremely unique vintage sterling silver and 14k sponge coral hessonite garnet ring. Organic textured red and lighter pink sponge coral cabochon set in a bezel of 14k gold. The ring slides into a band (with the coral cabochon slightly raised) with an orange hessonite garnet on the side - small round faceted garnet with five small triangular stamps around it, making it resemble a star. Almost a medieval wax seal style hallmark of “M” on the back of the band (usually this means the ring is European, specifically Russian or French, but given the stamps on the inside I can’t guarantee this). Size 7, the cabochon is raised about 3/8 inches, 6.97g. BKP