At the same time that demand may ease, silver's supply is increasing. New mines have come online recently, bringing a surplus of product to the market.

"That could weigh on the price of silver," says Joe Foster, portfolio manager of the Van Eck International Gold Fund (INIVX). "Meanwhile, the supply of gold is tighter due to declining gold production. However, I think silver will follow gold wherever it goes. If gold makes new highs, then silver will make new highs too. Silver is a much thinner and more volatile market. It takes a lot less demand to get the price moving higher."

Platinum

Unlike gold and silver, fundamental supply and demand drives platinum much more than the investment market. And for the past four years, there have been supply deficits.

Approximately 80% of the world's platinum comes from South Africa. For more than a year, electrical problems and rolling blackouts in South Africa have created supply disruptions. The mines are still not running at full capacity. Yet, as supply tightens, demand increases. This sparked the rally that pushed platinum to a high of $2,278 in March. Investor demand for the Platinum ETF in London also pushed the metal higher. But platinum is extremely volatile, and like gold and silver, it experienced a correction.

A large part of the platinum market goes into catalytic converters for cars. Signs of an economic slowdown in the U.S., including falling demand for cars, pushed platinum sharply lower in July. On Thursday, it closed at $1,744. Yet, even as U.S. auto demand falls, worldwide demand, especially in Asia, continues to rise.

"Demand is expected to be strong even though the U.S. is flirting with recession, because economic growth will still be positive globally," says David Jollie, publications manager at Johnson Matthey, a refiner and manufacturer of platinum products. "Platinum is used for computer hard discs and that demand is rising."

Jollie says it's difficult to tell where platinum will end the year because the commodity market looks weaker than six months ago. There is upside potential, but the signs aren't clear.