Everything you wanted to know about Ethiopian Opals. What are the types of opal they produce? Where is each type from? What are their characteristics? How big do they get? Which varieties you should avoid and which to focus on for cutting? What patterns do they have? How can you tell a treated opal from a natural opal? What's the difference between a Mezezo, Welo and a crystal? Black opals? Everything a new opal cutter wants to know......