If the trimmed matrix opal has already been shaped and sanded into a workable piece and the best fire band has been exposed. It is ready to be given a final shape and then polished.
For added luster pre-polish throughly on 14,000 diamond. Final polishing is best done with optical grade cerium oxide on leather.
One key to polishing Honduras matrix opal well is to create drag and heat. The tough volcanic rock will not polish effectively otherwise. Due to the small amount of opal in relation to the rock, the proper cutting technique should be applied to the basalt, not the opal. The other key is to have patience; it takes three to five times longer to polish effectively. Say, about 15 minutes of intense polishing. Use a good amount of polish to achieve optimum results.
Other important Tips:
Tip #1 After polishing the matrix swipe it with a black felt tip marker and rub the surface vigorously with a cotton towel. This will darken all of the tiny surface pits where the polishing compound is embedded.
Tip #2 Remove the stone from the dop stick, place it in a small oven safe container. Pour Opticon Fracture Sealer (Resin Only) in the container till it covers the stone. Place the container in an oven, preferably a small toaster oven and set it at 250-300 for 15 minutes. Turn the oven off and let it cool overnight. Next, take the stone out of the resinous Opticon and scrape off the excess, it is reusable. Wipe the stone clean with a paper towel and ten thoroughly with a cotton towel, Viola! A spectacular black matrix opal! Heating the matrix opal in Opticon drives off any excess water in the rock and replaces it with the resin.
Fine Honduran black matrix opals sell from $10.00 to $120.00 per carat when finished.
Have fun cutting!