Angelar's skin

Angelar's skin, also seen as aasimon's skin and angel's skin, was not a mineral but a coral found on reefs in shallow tropical waters.

Description
Proper preparation of these delicate pink 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,  possibly up to 200 gp in some areas.

Rumors & Legends
This gem got its name from the sorcerer Angelar, who (according to legend) became a wereshark with complete control over his transformations. The story tells that he consumed this coral in powdered form mixed into sea water and then cast polymorph self to become a shark. Another colleague then cast two more spells on him: water breathing, and Angelar's own invention, an arcane version of the divine free action spell. The legend goes on to say he achieved a long life, and that other wizards or even non-wizards could do as he did, if they could find trustworthy spellcasters to perform the regimen.