Note: Do not rely on this information. It is very old.
Bloodstone
Blood-stone, or Heliotrope, a variety of quartz, crypto-crystalline in texture and dark green in colour, with small spots of red jasper scattered through it, so as to resemble drops of blood. The name heliotrope, applied to a somewhat different stone, is explained by Pliny as due to the stone giving a red reflection of the sun's light when thrown into water. Blood-stone is found in the Isle of Rum, in Kintyre, and in the Deccan. It is chiefly used for signet-rings.