So this is the example of Regency you want to back when setting it. It is a flat cabochon at only 3mm thick. If you back it with something black when setting the color are just gonna glow and the clear areas will look blue. Polished on both sides.
Visit my Sold cabochon Gallery to see past opals I have cut. You will find other examples of materials, shapes, sizes, colors, and in general see my work there. Some stones date back over 15 years in there. I don’t show everything I cut, just the ones I really liked over the years. Please let me know if you have any questions about those materials.
Its also important to visit your local rockclub if you have one near by. Its a
great place to start if you are new to gems and minerals. Thank you.