If your copper utensil hasn't changed color on the outside yet, it's likely because it's a mixed material. Copper is a relatively soft metal, so it's often combined with other metals to create a more durable alloy. This is why many copper utensils have a tin or nickel coating - it helps to protect the underlying metal and prevent it from tarnishing. To be sure, you can test the utensil with a copper sulfate solution. If the solution turns blue, your copper is pure.