Despite its odd name, crocus cloth has nothing to do with flowers. It is actually a type of sandpaper. Crocus paper's sanding surface is a collection of natural minerals adhered to a cloth backing. Although constructed similarly, crocus cloth's abrasive surface is much finer and gentler than traditional sandpaper. Consequently, it is often used to polish metal, wood and gemstones.
Hold the crocus cloth in your hand or mount it onto a belt sander according to the manufacturer's instructions.
Sand the wood, metal or gem with the crocus cloth. Keep sanding, using medium pressure until the surface has the same texture or dull finish.
Wipe the surface clean with a tack cloth to remove any sanding dust.
Observe the finish. If you feel or see deep sanding grooves you would like to eliminate, switch to a finer grained crocus cloth. For example, if you started with coarse grain to smooth rough gems, switch to medium grain, then to fine to enhance the shine and even the surface. Wipe with a tack cloth after every sanding.
Polish, buff or otherwise finish the surface of the metal, stone or wood, if desired.