Beautiful sterling opal is a stone that develops in seas that are high in silica. Its name derives from the Sanskrit word Upala, which means precious stone, but it was more often known as Opallios throughout the Roman era. There are two different varieties of opal: valuable opal and ordinary opal. Opals stand for amplitude, hope, and purity. Opal Jewelry does not have a crystal structure, yet it appears to be an amorphous solid. In combination with pink tourmaline, it is the birthstone for the month of October.