Cabochons

Cabochon's 

A cabochon from the Middle French word caboche (meaning "head"), is a gemstone which has been shaped and polished as opposed to faceted. The resulting form is usually a convex (rounded) obverse with a flat reverse. Cutting en cabochon (French: "in the manner of a cabochon") is usually applied to opaque gems, while faceting is usually applied to transparent stones.