Fully saturated, opaque, and outside conventional grading- there is no clarity scale for a stone light does not pass through. What a black diamond offers instead is surface: a hard graphite luster closer to metal than to gem, and an outline that stays sharp against any setting.

Named for the way its facets open from a central point. Domed above, flat below, no pavilion and no culet. Cut since the sixteenth century and never about brilliance- it glows rather than flashes. The flat base gives it a broad face for its weight, and the shallow depth lets you see into the stone rather than off it.