The price of gold fell 4% to its lowest in more than five years, as talk of a rise in US interest rates this year led investors to sell.
Spot gold fell to as low as $1,088.05 (€1,003) in Asian trade - marking its lowest price since March 2010.
Investors turned to the US dollar, which rose on the likelihood of the Federal Reserve raising rates because of a stronger US economy.
Investors generally buy gold as a safe haven during times of uncertainty.
But Monday was the first time the metal has traded below the key threshold level of $1,100 (€1,014) since 26 March 2010.