Green rouge is a polishing compound composed principally of chromium oxide (Cr₂O₃), a fine-grained abrasive powder that imparts a high, mirror-like finish to hard metals. In the jewellery workshop it is most closely associated with platinum, stainless steel, and white-gold alloys — metals whose hardness and optical demands require a compound that cuts finely without introducing visible scratches or excessive heat. It is available in bar form (the abrasive bound in a waxy or grease matrix) and as loose powder, and is applied to felt, leather, or soft muslin buffs mounted on a polishing motor or pendant drill.

Composition and Abrasive Character

Chromium oxide is a dark, grey-green powder with a Mohs hardness of approximately 8 to 9, making it harder than most of the metals it polishes yet fine enough in particle size — typically in the sub-micron to low-micron range — to produce a refined surface rather than a scratched one. This combination of hardness and fineness is what distinguishes green rouge from red rouge (iron oxide, Fe₂O₃) and yellow rouge: red rouge is softer and better suited to gold and silver, while green rouge's greater hardness is necessary to work the tightly packed crystal structure of platinum and the chromium-bearing alloys used in stainless steel.

Because the compound generates minimal frictional heat during use, it is well suited to precision and delicate work where thermal stress could affect set stones, solder joints, or fine filigree. This low-heat characteristic also makes it the compound of choice in optical and surgical-instrument polishing, industries in which surface integrity is critical.

Use in the Jewellery Workshop

Platinum finishing represents the most common application of green rouge in professional jewellery manufacture. Platinum's hardness (approximately 4 to 4.5 on the Mohs scale in its pure form, higher in alloyed states) and its tendency to show fine surface marks mean that the polishing sequence typically concludes with green rouge on a soft muslin or felt buff after earlier stages using harder abrasive wheels or tripoli compound. The result is the dense, liquid-bright surface that distinguishes well-finished platinum from lesser work.

White-gold alloys — particularly those containing palladium or nickel — respond similarly, and green rouge is frequently used as the final step when a high white polish is required. For yellow or rose gold, red rouge remains conventional, as the softer abrasive is sufficient and avoids any risk of micro-scratching.

Standard workshop practice calls for a dedicated buff for green rouge, never shared with other compounds, to prevent cross-contamination that would compromise the final surface. The compound is applied sparingly to a rotating buff and the workpiece brought lightly into contact; excessive pressure defeats the purpose of a fine finishing compound.

Forms and Availability

Green rouge is sold in compressed bar form — the most common format in jewellery supply — as well as in loose powder for specialist applications. Bar rouge is convenient for charging a buff directly at the polishing motor. Powder form is used where the compound must be mixed into a slurry or applied by hand to a flat lap or strop, as in some optical and lapidary contexts. Both forms are widely stocked by jewellery tool suppliers and are not hazardous in normal workshop use, though respiratory protection is advisable when working with the loose powder to avoid inhaling fine chromium oxide particulate.