Historical superstitions( From Wikipedia)
In the Middle Ages, opal was considered a stone that could provide great luck because it was believed to possess all the virtues of each gemstone whose color was represented in the color spectrum of the opal.
It was also said to confer the power of invisibility if wrapped in a fresh bay leaf and held in the hand. Following the publication of Sir Walter Scott's Anne of Geierstein in 1829, however, opal acquired a less auspicious reputation. In Scott's novel, the Baroness of Arnheim wears an opal talisman with supernatural powers. When a drop of holy water falls on the talisman, the opal turns into a colorless stone and the Baroness dies soon thereafter. Due to the popularity of Scott's novel, people began to associate opals with bad luck and death. Within a year of the publishing of Scott's novel in April 1829, the sale of opals in Europe dropped by 50%, and remained low for the next twenty years or so.
Even as recently as the beginning of the 20th century, it was believed that when a Russian saw an opal among other goods offered for sale, he or she should not buy anything more since the opal was believed to embody the evil eye.
Opal is considered the birthstone for people born in October or under the sign of Scorpio and Libra.
Opal is the national gemstone of Australia, which produces 97% of the world's supply. This includes the production of the state of South Australia, which accounts for approximately 80% of the world's supply.
Opal is used as a gem in jewelry
Queen Maxima of the Netherlands often wears opals
There are opals in many colours.