Gold

You'll need to acid test your gold to see if it is pure. I'd advise not to do this, and instead send it to a lab, if you are curious. According to Barrick Gold, the largest gold producer, gold is running out. Exploration companies are finding less and less every year, and producers are making less and less every year. In addition, the demand is going up and up, so the prices are going higher and staying higher. Whatever you do, don't buy gold online, unless the item for sale is from an accredited dealer. And if you buy, make sure to buy bullion coins and bars with certification, that way you know it is pure and you wouldn't have to test its purity.