I use tin oxide. Seems to work best for all different types of stones.
Here's a guide I use.
INTRODUCTION
1. Many stones polish equally well with several buff and polishing compound combinations. A very hard gem can be polished by a much softer polish powder. Only one polishing agent should be used on a buff.
2. Polishing does not remove any material from the surface. If scratches develop, the stone must be re-sanded.
3. It is impossible to obtain a high glossy finish on very soft materials, especially if they tend to be slightly porous, fibrous, or granular. As a last resort with this type of material, a finish gloss can be given by the use of spray varnish.
BUFFS
Canvas: Canvas is useful when polishing heat-sensitive stones because it develops very little friction.
Muslin: Muslin buffs are recommended for soft stones and gems that are heat-sensitive.
Leather: Leather is a versatile buffing material that is both efficient and economical. Leather generates heat,
but not as much as felt.
Felt: Felt is useful for polishing glass and stones of even texture. It is not recommended for gemstones that
under cut. Friction on felt generates heat rapidly.
Phenolic: Phenolic tools or phenolic lap disc (cab laps) are useful when impregnated with diamond grit.14,000
Micron (pre-polish) or 50,000 Micron (polish) diamond compound can be applied to the surface of
the gemstone and worked with a phenolic carving tool. It can also be applied to the surface of a phenolic lap
disc and worked with the gemstone mounted at the end of a dop stick. The diamond will charge the phenolic
plate making smoothing and polishing easier.
POLISHING COMPOUNDS
Cerium Oxide: Covington cerium oxide will polish at a faster rate than conventional polishing compounds
and produce a superior optical lens surface with no staining or caking. Because it will polish faster, a lower
concentration can be used. It is recommended for use on leather, felt, polyurethane foams, and thermoplastic
polishing pads. It is a favored polish for quartz type minerals and other gemstone types. It is not recommended for gemstones that will under cut.
Linde “A”: A .3 micron aluminum powder that is carefully graded for uniformity of grain size. It is excellent for polishing stones that will under cut. Excellent for hard to polish stones.
Chromium Oxide: Chromium oxide is a hard polishing agent. It is green in color and stains badly. It is useful for polishing jade and stones that will under cut.
Tin Oxide: Tin oxide is an excellent general-purpose polish. It is used to provide a final high gloss finish.
Diamond: Diamond grit is the most efficient polishing medium. It is especially useful for polishing difficultto-
polish stones.