A mid 16th/early 17th century gold and enamel 'memento mori' ring   The heavy gold ring with flattened quatrefoil bezel the centre with painted white enamel skull on black enamel ground, the border with black enamel legend mememto mori the engraved scrolling shoulders with traces of white and green enamel, the reverse with indistinct goldsmith's privy mark, circa 1600,