Covington buff & polish chart

This comes from the Covington Catalog

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.
Polishing does not remove any material from the surface. If scratches develop, the stone must be re-sanded.
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.

	buff					polishing compound
material	canvas	phenolic	felt	leather	muslin	cerium oxide	chrome oxide	diamond	linde "a"	tin oxide
agate		c	a	b		a-b		c
amethyst		c	a	b		a-b		c
beryl		d	a	b-c		a	c	d	b
calcite				b	a					a-b
chloastrolite			a			a
feldspar			a			a
garnet		c	a-b			b	a	c
glass						a
goldstone						a			b
hematite	b				a	a			b	a
howlite			a	b					a	c
jadeite				a-b	c		b		b
jasper			a	b		a			a
lapis lazuli				a-b			b		a
malachite				a-b			b		a
nephrite-jade				a-b	c		b			c
obsidian			a			a
opal-australian			a		b	a				b
opal-mexican		a						a
psilomelane				a-b					a	b
petosky stone	a									a
quartz		c	a	b		a-b		c
rhodochrosite				a-b					a	b
rhodonite				a-b		b			a
serpentine				a-b					a	b
sodalite			a			a
thomsonite			a			a
tigers eye				a					a
tourmaline	c			a-b			b	c	a
turquoise				a-b					a	b
unakite			a			a
variscite			b-c	a		b			a	c
wonderstone			b-c	a					a	c
Match letters across rows for best combinations

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.
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.

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 difficult-to-polish stones.

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