Valley Goldmine Portland also serves as gold buyers for Tigard, Oregon for customers looking to sell gold in Tigard. Valley Goldmine Portland buys gold silver and platinum in the forms of jewelry, coins, bullion, scrap gold, dental gold, sterling silverware, and more. FUN FACTS: Gold is a dense soft metal with a bright yellow color. It is the most malleable of all metals and retains its luster without tarnishing in air or water. It is also a good conductor of heat and electricity.