Angelar's skin

Angelar's skin, also called angel's skin, was not a mineral but a delicate pink coral found on reefs in shallow tropical waters.

Description
Proper preparation of these fancy stones included baking in the sun for many days to dry them out and to eliminate the odor of dead sea life. It could then be worked into jewelry but had to be protectively mounted to avoid accidental breakage. A typical specimen had a base value of 100 gp.