a pitch-black spinel

Cut into a a multifaceted teardrop, the spinel shines with a mirror finish of pitch-black brilliance. The base of the gem is smooth, while the point at the top of the teardrop is as sharp as a needle and as strong as steel.

It is a pitch-black spinel.
It weighs about an ounce.

You identify a pitch-black spinel.
It weighs eleven drams, and it is worth about two lauren.
Its keywords are spinel, pitch, black, gem, and jewel.
When embedded, it can be used to shroud yourself in shadows.