Rhodium
Rhodium is a blue-white metal resembling aluminum, hard and brittle. It has high reflectivity. Upon heating, it becomes malleable. Density: 12.41; melting point: 1960°C; hardness on the Mohs scale: 6.0. Chemically resistant. Under normal conditions, it does not oxidize in air or water. When heated, it forms a black oxide film that disappears at temperatures above 1200°C. Rhodium is resistant to the action of acids (except concentrated sulfuric acid) and aqua regia. It is also resistant to the action of sulfur, chlorine, and fluorine. Used in jewelry as a decorative protective coating for jewelry items
Source: Federal Customs Service of Russia dated 20.01.1999 № 01-15/1361
"On the Issuance of Instructions and Methodological Recommendations"
(together with "INSTRUCTION ON THE PROCEDURE FOR TRANSFER, RECEIPT, ACCOUNTING, STORAGE AND HANDOVER OF ITEMS SUBMITTED FOR EXPERT EXAMINATION TO CUSTOMS LABORATORIES AND CONTAINING PRECIOUS METALS AND STONES", approved by the Federal Customs Service of Russia 11.01.1999 № 01-23/1359, "METHODICAL RECOMMENDATIONS ON THE PROCEDURE FOR INSPECTION OF JEWELLERY ITEMS CONTAINING PRECIOUS METALS AND STONES WITH PARTICIPATION OF A SPECIALIST AND REFLECTION OF ITS RESULTS IN THE PROTOCOL", approved by the Federal Customs Service of Russia 11.01.1999 № 01-23/1360)