A cabochon or cabachon is a gemstone which has been shape and polished as opposed to facetted. The resulting form is usually a convex top with a flat bottom. Cutting "en cabochon" is usually applied to opaque gems, while facetting is usually applied to transparent stones. Hardness is also taken into account as softer gemstones with a hardness lower than 7 on the Mohs hardness scale are easily scratched, mainly by silicon dioxide in dust and grit. This would quickly make translucent gems unattractive - instead they are polished as cabochons, making the scratches less evident.