Carving Opals With Thin Fire Layers

Cutting through a thin layer to expose greater fire is a common challenge when carving opals. I had an opal in my scrap box for years that didn’t interest me. One day, after a close inspection, I saw a red broad flash under the pinfire. I didn’t much care for the stone as it was, so I decided to cut it deeper.

The picture below shows the stone when I started. The top has been sanded to show fire. At this stage, the opal weighed 6.51 carats. It had no tapering on the sides, and the back wasn’t sanded. There was a half-carat waste in shaping this stone, so its maximum size potential was about six carats.

Carving Opals - flash under pinfire

Using a Cratex Wheel

I began by simply sanding it on a 600 wheel. The red broad flash became more visible, but I was rapidly losing fire around the edges. Since the fire layers weren’t flat, the stone needed to be cut lower in the center. So, I took a wide Cratex wheel and began cutting into the fire layer, working from the center out. (See Cabochon Carving Tools and Techniques for more information on the…