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How to Polish Black Opal

Black opal is the rarest type of the lustrous gemstone opal. It was first discovered in the late 1800s at Lightning Ridge, north of Sydney, Australia. This is the largest known deposit of black opal in the world. Opal differs from crystal gemstones such as rubies and sapphires in that it is actually a rock. It is comprised of many crystallized structures, and the spaces between these crystals cause black opal to be very porous. This can be a problem when it comes to cleaning and polishing black opal, but there are steps you can take to ensure this gem remains sparkling.

Things You'll Need

Waterproof emery paper or sandpaper
Automotive polishing compound
Cloth

Instructions

- 1
  Place the emery paper or sandpaper on a flat surface for support on top of a cloth, which will serve as a cushioning for the paper. Keep the paper wet throughout the whole process. Emery paper, which is made with the hard mineral emery, is made for sanding rough surfaces and is tougher than sandpaper. Either type will work, though make sure it is waterproof. You may need several different grades of paper, though they should all be very fine texture.
- 2
  Begin polishing the black opal with emery paper by folding the paper and cloth backing over the opal. Reapply water to the paper as needed to keep the stone wet.
- 3
  Apply a small amount of automotive polishing compound or scratch remover to the black opal and begin to rub it in with a cloth. Do not use car wax or cleaner wax. Alternatively, you can use a small amount of plain toothpaste.

Gemology