Gold. Silver. Platinum. Palladium.Want more than a piece of paper with a stock number on it to show for your investment? Then learn about all the ways you can add precious metals to your portfolio.Gold and silver have been king and queen of metals for centuries. Today, they are joined by platinum and palladium in the precious metals arena. They are traded in the form of bars, rounds and ingots, tangible assets you can see and touch.