According to Portal, in Classical antiquity rubies were regarded as emblems of good fortune. 'It was an evil omen if they changed colour, but they would regain their blood-red tint as soon as trouble had passed. They banished sorrow, restrained lust, resisted poison, were preservatives against plague and warded off evil thoughts'.
Like anything red, a ruby may symbolize passion: love or anger.
Like any other jewel, a ruby may be a symbol of your true self. The context will usually tell you which of these meanings applies.
As a blood-stone, the ruby was used homeopathically in the preparation of medicines to staunch bleeding. For the same reason, Russian popular tradition maintains that it is good for the heart, brain, memory and vitality and that it clears the blood. However, if we are to believe good Bishop Marbodius, it is the solitary and glowing eye which dragons and wyverns carry in the middle of their foreheads. It is then known as a carbuncle. They 'surpass all other fiery stones, casting rays like blazing coals, so that the darkness is quite unable to dim their light'.