BASIC 2. More than 90% of the world's precious opals come from Australia, and the rest can be found in other parts of the world such as Mexico, Brazil, Indonesia, Czech Republic, Ethiopia and USA.Opals from Mexico (called Mexican Opal) has more water and is transparent or extremely translucent.ASIC 2. More than 90% of the world's precious opals come from Australia, and the rest can be found in other parts of the world such as Mexico, Brazil, Indonesia, Czech Republic, Ethiopia and USA.