By Artisanal Silversmithing & Gemology Review Board
A technical look at rhodium plating: galvanic electrodeposition, 0.5 to 2.0 micron thickness standards, preventing copper oxidation, and achieving mirror-finish white brilliance.
Rhodium, a rare member of the platinum group metals (PGM), provides fine sterling silver and white gold jewelry with exceptional hardness, corrosion immunity, and a luminous mirror finish.
1. The Galvanic Electrodeposition Process
Plating Parameter
Technical Specification
Impact on Jewelry Longevity
Plating Metal
Pure Rhodium (Rh, Atomic #45)
Exhibits 6.0 Mohs hardness; totally inert to atmospheric sulfur
Layer Thickness
0.75 μm – 1.5 μm (Microns)
Optimal commercial thickness for rings, pendants, and bangles
Bath Chemistry
Rhodium Sulfate in Sulfuric Acid
Ensures atomic-level cohesion and high-reflectivity surface
Tarnish Prevention
100% Barrier against Hydrogen Sulfide
Prevents silver-copper alloy contact with ambient air moisture