Precious, rare, beautiful, and tough—rhodium is aptly named. A member of the platinum family (group) it is by far the most expensive precious metal, costing 6 times as much as gold—that’s $6,000 per troy ounce as of May 2006. Often used to simulate the rich appearance of platinum, many people do not know that of the two, rhodium is the more precious. It is also brighter than platinum, and in a specular comparison of reflected light on highly polished electroplated metal surfaces, rhodium reflects 72%-80% as compared to 65% for platinum and 60% for gold. By contrast, a highly polished silver finish will reflect more than 95% of all incidental light rays, while highly polished rhodium finishes absorb more of the visible light spectrum. However, the tradeoff in silver being softer, thus more susceptible to scratching and abrasion, and requiring high maintenance to look its best, makes rhodium an ideal finish that keeps its looks and lasts over time. (1) Please see notes.
With a melting point of 3567 degrees Fahrenheit, rhodium is also extremely hard (second only to nickel), and has both a higher melting point and lower density than platinum. Its industrial use is primarily as an alloying agent for hardening platinum and palladium. Its use in jewelry, to beautify and enhance durability. (2)Please see notes.In terms of rarity, rhodium is the rarest of them all with annual world production of the silvery white metal a mere 20 tons. About 80% comes from South Africa, in river sands of the Ural Mountains, South America, and various areas of North America including the copper-nickel sulfide mining area of Sudbury in Ontario, Canada. The industrial extraction process is a complex one, as rhodium occurs in ores mixed with other metals such as palladium, silver, platinum, and gold and is obtained free as a white inert metal which is very difficult to fuse.
Rhodium Plating Gives Jewelry Durability and Pizzazz
Over the last 40 years, advanced techniques and significant technical refinements to rhodium electroplating processes have made it an excellent choice for use in jewelry making and other decorative applications. Rhodium is deemed so special that it is used when other precious metals just don’t seem to be elaborate enough to use in creations that honor someone or something. For example, in 1979 the Guinness Book of World Records gave Paul McCartney a rhodium-plated disc for being history’s all-time best-selling songwriter and recording artist. Similarly, Guinness has listed items such as the world’s ‘Most Expensive Pen’, and Most Expensive Board Game’ as containing rhodium. (Courtesy Wikipedia). So, literally and symbolically, rhodium holds the honor of the world’s ‘most precious metal’.As a protective coating for jewelry, rhodium adds spectacular polish, dazzling shine, and unbeatable durability. Its remarkable characteristics eliminate the possibility of surface discoloration and tarnish, even when exposed to extreme environmental conditions. Highly resistant to abrasion and scratching, a rhodium-plated finish is the ideal choice for protecting and beautifying white gold and particularly, sterling silver.
Ultimately, a rhodium-plated piece of jewelry provides indefinite wearability without the need for frequent cleaning and polishing. Your beautiful rhodium-plated jewelry will stand the test of time, and surely become treasured family heirlooms.(3) Please see notes.
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(1)A specular measurement attempts to quantify the amount of flux (light) reflected from the smooth surface of an object at a given angle.
(2)Hardness Comparison – The MOHS hardness scale measures a metal’s ability to resist marking from surface abrasion and lateral directing scuffing—it is more suitable for gemstone evaluation and not widely used for metal surfaces, although the values are an interesting reference.
MOHS Scale
Rhodium is 5.5
Silver is 3.25
Gold is 2.75
Platinum is 4.3
Nickel is 7.0
(3)For examples of beautiful, high quality rhodium-plated jewelry visit The Hollywood Collection.
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