Bloodstone

Bloodstone, or heliorope, is a variety of jasper; particularly the green form with inclusions of red hematite, supposedly resembling spots of blood; hence the name bloodstone.

Heliotrope features as an invisibility stone in one of Boccaccio's stories in the Decameron and as an healing magic item in a musical comedy derived from it.

Heliotrope is sometimes used in carved signet rings and is the traditional birthstone for March.