Jewellers' rouge is a fine red polishing compound based on hematite or related iron oxide powders, used at the bench for the final mirror finish on gold, silver, and other soft-metal jewellery surfaces. The name derives from the colour, and the substance has been a workshop staple since at least the eighteenth century. It is supplied either as a hard wax stick that is loaded onto a cotton or felt buffing wheel, or as a liquid suspension for hand polishing.

Composition and Action

The active material is ferric oxide, Fe₂O₃, milled to particle sizes typically between 0.5 and 5 microns. The very fine grade, sometimes called red rouge, is the slowest cutting and gives the brightest final finish. White rouge, based on tin oxide or aluminium oxide, is a faster-cutting alternative used for harder white metals including platinum and certain stainless steels. Green rouge, based on chromium oxide, is used principally on platinum and on the highest-grade rhodium-plated surfaces.

Rouge works by a combination of fine abrasion and surface compression. Used correctly on a soft buff at moderate speed, it removes only the residual marks from a previous tripoli or pumice cut and produces a final reflective finish without removing significant metal. Used aggressively or on too-firm a wheel it can round detail and obscure engraved lines.

Workshop Practice

The standard sequence in goldsmithing is to finish the piece through emery or silicon carbide papers, then through tripoli compound on a stitched calico wheel, and finally with rouge on a soft loose-leaf cotton wheel. Cleaning between stages is essential, since contamination of a rouge wheel with coarser tripoli will scratch the surface rather than polish it. Many workshops dedicate separate wheels and even separate motors to each compound to prevent cross-contamination.