Bloodstone is a variety of dark green chalcedony spotted with red is also known as Heliotrope.
Bloodstone was once used as an amulet in the belief that it could stop bleeding. It was also said to be able to turn the sun red and to make thunder and lightning occur. It was supposed to give the wearer clairvoyance while preserving his faculties and health.
Medieval Christians often used bloodstone to carve scenes of the crucifixion and martyrs, causing bloodstone to be also called martyr's stone. One legend of the origin of bloodstone says that it was first formed when drops of Christ's blood fell and stained some jasper found at the foot of the cross.
Bloodstone was well known to Aztecs which used it to regulate the bloodflow.
Even today, finely powdered bloodstone is used as a medicine and aphrodisiac in India.
Bloodstone alternates with aquamarine as the birthstone for March.