French 18k gold diamond-shaped pendant c. 1810, converted or taken from some larger piece of jewelry. Or was it once a button? Black imperfect enamel has some chips and is worn (visible under magnification and if you get really, really close). A silver collet-set table cut diamond w/ foil back has some darkening of foil. Nice big square stone looks old AF! Weight: 1.11 grams. Diamond size: approximately 4.5 x 4 mm. Hallmarks lost. Just over 1/2" long, not including bail at top.