rhodium

It is not usually the main metal in a piece of jewelry, but it is often the reason jewelry shines so brightly. This rare, silvery-white metal belongs to the platinum group and is much rarer than gold or silver. Its strong resistance to corrosion makes it very useful in catalytic converters in cars, where it helps reduce harmful pollution from exhaust fumes. It is also used in some metal mixtures and as a plating for jewelry. When you see "rhodium-plated" silver or white gold, it means a thin layer of this precious metal has been added to give it a bright finish and help protect it from tarnish.

Rhodium (pronounced ROH-dee-um) is an exceptionally rare, silvery-white, hard, and corrosion-resistant metallic element. Discovered in 1803 by William Hyde Wollaston, its name is derived from the Greek word rhodon, meaning rose—a nod to the deep rose-red color of the salts produced during its extraction. You won't find rhodium nuggets in a riverbed, however; it is almost exclusively obtained as a byproduct of platinum and nickel mining, which makes its global supply incredibly limited.

While it may not be a household name, rhodium is a silent workhorse of modern industry. Over 80% of the world's supply is used in the catalytic converters of automobiles to reduce toxic emissions. Because it is so scarce, its price can fluctuate wildly, often soaring well above the price of gold. Beyond the automotive industry, rhodium's extreme durability makes it perfect for high-wear electrical contacts, high-temperature thermocouples, and laboratory equipment. In the world of luxury, rhodium plating is the industry standard for giving white gold and sterling silver a mirror-like shine while protecting the softer metals underneath from scratches and tarnish.

Interestingly, rhodium is also prized in the construction of high-end mirrors due to its exceptional reflectivity. Whether it is cleaning the air you breathe or adding a permanent sparkle to a wedding ring, rhodium remains one of the most versatile and valuable elements on the periodic table.