Crooks aren’t nice people, they hurt people, and we don’t like to write about them. But the fact remains that if we look at crime trends around the country, they can teach us some lessons about the value of precious metals. Also, because crooks make money by selling what they have stolen, their crimes tell us there is a market for the metals they are selling.

We’ve already written about pink gold, rose gold, white gold, and even green gold on the Specialty Metals blog. (See related posts below.) We thought we’d seen just about every color, then we found an article entitled “What Can Make a Piece of Gold Turn Blue?” that Esther Inglis-Arkell wrote for io9.com. 

You have probably seen niello without knowing what it was. It looks like black enamel that has been painted into the indentations around geometric patterns on the surface of decorative silver belt buckles, goblets, candlesticks and other objects. But niello isn’t paint. It is actually a compound made of silver, sulphur and other chemicals.