Bloodstone

Bloodstone, or heliotrope, is a variety of jasper; particularly the green form with inclusions of red hematite, supposedly resembling spots of blood; hence the name bloodstone. It features as an invisibility stone in Boccaccio's Decameron, and is sometimes used in carved signet rings and is the traditional birthstone for March.

"Last Call"
In "Last Call", maenad Meditrina Bassarid buys some bloodstone from Bert Decker, using Herbert Orson Caine as a middleman.