Platinum and palladium exchange traded funds (ETFs) are reflecting the love investors have for metals that do much more than look pretty.

Platinum demand is being driven, literally, by its primary use as a catalyst in devices that remove automotive pollutants, says Carolyn Cui for the Wall Street Journal. Thanks to tightening emissions standards and a growing global auto population, demand for the metal has risen 8.6%.

Factor in the personnel, production and equipment woes of mining companies already struggling to keep up with demand, and you’ve got rising prices. South Africa’s electricity outages earlier this year also pushed the price of metals, including gold and platinum, to new highs. Platinum is 12% off its high.

Since ETFs that hold physical platinum were launched by London’s ETF Securities last year, the price of platinum has risen 52% and palladium is up 20%.