Really enjoyed visiting Lightning Ridge Opal mines. Their store was right behind our hotel the Westin. My partner and I were so interested in all they had to show we stayed for a couple hours getting information on opals how they are graded, the various types....we even got to give a go at grinding and polishing. They seemed happy to just let us hang around. No pressure to buy, but we sure looked. Much more than a shop. It was fun.