This was a large job. I cut 108 total finished Ethiopian Opals from a parcel of rough stones. I began by trimming the rough stones, cutting small slabs, then gluing dop sticks (nails) to their backs, making them easier to hold during the cutting process. I used by Pixie Machine to grind the finished outline shape and smooth a domed top surface. My Pixie is configured with grinding wheels beginning with coarse on the left and successively smoother to the right - one metal backed 220 grit, and five sponge backed wheels 280 grit, 600 grit, 1200 grit , 3000 grit, and 8000 grit.
The initial outline shape and domed top are shaped using the first two wheels. Then the surfaces are smoothed using each each successive wheel, just long enough to remove the scratches made by the prior wheel.
The stones become well polished after being worked with the 8000 grit wheel.
When a mirror polish is not brought out with the 8000 grit wheel, I use the leather pad for final polishing. The leather disc is on the right side of the cabbing machine (see photo). A short mist spray of Holy Cow polish is sprayed on the leather and then the top of the cabochon is buffed. Another method used to bring up a final polish is to use a cotton buffing wheel with polishing compound.