If your birthday is in October you can consider yourself lucky to have the Opal as your Birthstone.
Some fun facts about Opal:
Opal was the favorite gemstone of Queen Victoria. She had access to diamonds, rubies, and sapphires from all around the British Empire but was in love with the intoxicating colors of the opal.
Opal is formed when there is seepage of rainwater into the crevasses inside rocks. After the water evaporates, the silica left behind dries and hardens into the valuable opal.
Believe it or not - opal has been discovered on Mars. It is one among the few gemstones, which have been discovered outside our planet.