What is Jeweller's rouge ?

Jeweller's rouge is chemically identified as ferric oxide (Fe2O3), also known as iron(III) oxide [t2][t3]. It is a very fine, red-colored powder used primarily as an abrasive for the final polishing of precious metals like gold and silver, as well as lenses and glass [t1][t10]. While other polishing compounds are sometimes colloquially called rouge, true jeweller's rouge specifically contains this iron oxide, often mixed with a binding agent like tallow or wax to form a solid bar or paste [t2][t3]. It is valued in the jewelry trade for producing a superior, high-lustre finish on soft metals [t4]. Ferric oxide is distinct from ferrous oxide (FeO), which is rarer and chemically different [t3]. Historically, this compound has also been used as a cosmetic and a pigment known as Pigment Red 101 [t1][t7].

Sources

1. [1] https://pubchem.ncbi.nlm.nih.gov/compound/518696