Burned facet

Burned Facet: This facet may appear whitish, or burnt, as a result of the cutter polishing the facet "against the grain".
Cabochon - An unfaceted cut stone of domed form (having a convex surface). Often called a "cab." ...

Polish Mark: Surface clouding caused by excessive heat (also called burn mark, or burned facet), or uneven polished surface resulting from structural irregularities.

(A burned facet has a milky appearance - as if the diamond needs cleaning.) These characteristics are evaluated and rated on their overall impact on the beauty of the diamond.

See also: Polishing, Surface, Polish, Feathers, Girdle