Blood Rubies (otherwise called Earth Rubies in the Harmony Gold English version, and known as Rich Stones in the original Japanese version) are a type of valuable ruby that are located in the bottom of the Land of Gurumes. Those rubies are cursed and deteriorate everything around them.
King Gurumes paid Bongo and Raven in these in exchange for gathering the Dragon Balls for him. When Penny made a wish to Shenron to restore the land, all of the blood rubies were removed from the ground which seemed to have been behind all of the corruption.
- Frieza describes Planet Vegeta as looking like a blood ruby, shortly before destroying it. This could possibly mean that this resource can be found on other planets as well.
- Blood Rubies are Bullet proof, we know this because Yamcha uses them to survive being shot multiple times in the gut at one point when storming Gurumes Castle.