Opal has been thought by some to be unlucky, but it represents faithfulness and confidence. Some have held that opal will bring happiness and healing.
Tourmaline has a mixed history due to its frequent mis-identification as other stones due to its wide array of colors.
Opals can be one or many colors. The GIA has a good explanation of opal coloring.
Like Opal, Tourmaline is also available in an array of colors of the rainbow, but typically is only one color per stone.
Tourmaline comes from the Sinhalese word for “mixed gem” because when it was discovered, it was confused with Emeralds.
Opal 5.5 – 6
Tourmaline 7 – 7.5
Opal was used for tools in ancient Ethiopia, and as jewelry in later civilizations. Synthetic opals are used in optical and cosmetic applications.
Tourmaline is mainly used in jewelry and as gifts, especially in China.