Alchemist-hp/Wikipedia

Forget platinum and gold, a silvery white metal called rhodium is gaining notoriety after a cameo appearance in last night’s episode of “Two and a Half Men.”

More than 15 million viewers of the CBS sitcom may have taken notice when Ashton Kutcher proclaimed that his rhodium wedding band (not his actual Demi-related wedding band) was made of “the most expensive metal in the world.”  Soon after the episode aired, “rhodium” was trending online.

While it might have sounded like an exciting statement, it’s not entirely true.  According Steven Chillud, a research professor in the geochemistry division of Lamont-Doherty Earth Observatory at Columbia University, the supply and demand of rhodium creates fluctuations in pricing compared with gold. “There’s a hundred times more gold mined per year than rhodium,” says Chillud.

According to Deutche Bank, for every ounce of rhodium mined, there are actually 114 ounces of gold mined. However, gold can also cost more than rhodium since the demand is more consistent.

The reason, Chillud says, is that rhodium is mainly mined along with other metals, “which makes it expensive and [its] price varies dramatically.”

Element number 45 on the periodic table, rhodium was discovered by William Hyde Wollaston in 1804.

Part of the platinum family, it’s often used to plate white gold jewelry. In the modern era, rhodium has been used as a key component in the catalytic converter, which converts toxic exhaust emissions into less toxic substances, in automobile engines.

While rhodium remains in demand by jewelers, the recent economic downturn in the auto sector lead to a drop  in rhodium prices, says Chillud. Rhodium plummeted  from a high of $10,000 in 2008 to approximately $2,000 today.

With a price drop of nearly 80 percent, a rhodium wedding band might be a bargain after all.