Ruby, the birthday stone in July, represents success, love, courage and health. Ruby is older than diamond. In ancient India, because of the pure color of rubies, people at that time thought that rubies must be burning with eternal flames. In ancient Egypt, it was the symbol of the supreme king. In medieval Europe, rubies were regarded as the precious stones of God's mercy. Because the red color of ruby is like "pigeon blood", its red color is commonly known as "pigeon blood". People think that ruby has the ability to eliminate suspicion and jealousy of love, so it is also considered as the guardian stone of love. Ruby, a kind of corundum, is mainly composed of alumina, and the red color comes from chromium. Most natural rubies come from Asia, Africa and Australia, and there are some in Montana and South Carolina. Natural rubies are very rare and precious, but artificial rubies are not difficult, so industrial rubies are all artificial. In Europe, rubies are still regarded as the witness of marriage in royal weddings.