A men's sterling silver cabochon (cab-set) onyx ring made in .925 sterling silver and set with a 10mm x 8mm genuine black onyx stone.
The top shoulder of the ring's band measures 9.7mm wide and graduates to 3.3mm at the bottom. Top surface of the ring measures 12.2mm in size.
Also available in 10k, 14k, or 18k gold, shown below.