Adam's favourite stone out of all the gems of the world is Opal and it happens to be the birthstone for October. You've probably heard the superstition that this gem is unlucky to wear unless it's your birthstone. But for many ages they have been considered therapeutic, transformative and a symbol of hope. They were even used traditionally as an engagement stone, symbolising love and fidelity, before being pushed out of the market by 'envious diamond merchants'. Opals have been collected from Australia, Mexico and Peru, but recently a huge discovery has come from Ethiopia!