Hand crafted from sterling silver with cultured opals. These beautiful earrings are designed in Australia by Makers & Providers and ethically made by skilled artisans in Mexico. Approximate dimensions: 6mm x 7mm Cultured opals are also known as lab grown opals. These opals, rather than being mined out of the earth, are grown in a laboratory using silica and technology developed in Japan in the 1970's. In a controlled laboratory environment cultured opals can be produced in an amazing array of colours. They are actually stronger than natural opals. We recommend, as with natural opals, that they be removed when you come into contact with chemicals as this can be detrimental.