If you were born in October, consider yourself lucky, because you get to choose between two birthstones — tourmaline and opal. Since both of these are available, in a wide array of colors, there are endless possibilities for jewelry with these gems. According to legend, both of these birthstones came to the earth through journeys that included rainbows. Tourmaline’s color depends on trace elements in its chemical makeup, while opal diffracts light, to show a wide range of colors. For centuries, many people have associated opals with good luck. Ancient magicians used black tourmaline, to protect against evil forces and negative energy, which is shared by many people who wear this gemstone today.