(ˈ)sha|tōⁿ noun
( plural chatons -ōⁿ(z))
Etymology: French, from Old French chastun, of Germanic origin; akin to Old High German kasto container, Middle Dutch kaste barn, Old English bēo cere beekeeper, Old High German kar vessel, Old Norse ker, Gothic kas
1. : the head of a ring in which a stone is set or on which a device is engraved
2. : the stone set in a chaton
3. or chaton foil : a coating (as a foil or lacquer) applied to the back of a cheap gemstone to give it greater brilliancy