Opal stones Opal is the birthstone for the month of October, The name opal is thought to be derived from the Sanskrit upala, meaning "precious stone,” and later the Greek derivative “Opallios,” meaning “to see a change of color.” The opal is a stone so distinctive that everyone can identify it, with its many colored flashing lights. The brilliance and vibrant colors within an opal resemble the colors of fall, so it is an appropriate birthstone for the month of October. Opal is unique among gems, as it displays an array of very brilliant miniature rainbow iridescent effects, all mixed together. Among the ancients, opal was a symbol of fidelity and assurance, and in later history it became associated with religious emotional prayer It was believed to have a strong therapeutic value for diseases of the eye, and when worn as an amulet, it would make the wearer immune from disease as well as increase the powers of the eyes and the mind. It is a karmic stone- it encourages putting out positive emotions and teaches that what you put out comes back to you.