"This variation on a memento mori skeleton ring features the skeleton on a black ground beneath the central crystal (rather than the usual skull or hair seen in rings of this type). The band is a high-carat gold in a beautiful scrolled design with black enameling, and it memorializes the deceased: “J. Gardiner Ob. 19 May 1764 AE 51.” Two smaller crystals bookend the central crystal."
Rare book, Dramatic Color by Overprinting from Donald E. Cooke. This book contains Donald's permutation method and beautiful overprint examples. If you cannot access this book, you could consider "Seasons" which is illustrated by famed French comic artist, Blexbolex