Copper and its alloys have been around for centuries. Brass is an alloy made from copper and zinc, which is why it can be difficult to distinguish copper from brass. Luckily there are a few ways to tell which metal you have.
Compare your item to a known copper item. Set the two items beside each other and compare the color and the sound, looking for any difference.
Look at the color, which is the main way to tell the difference between brass and copper. Copper is a reddish brown metal that turns green when it corrodes, as evident by the Statue of Liberty. The color of brass varies based on the percentage of copper and zinc. Zinc causes the yellow tint most commonly associated with brass, which is why more zinc used in making the brass causes more yellow tones in the brass.
Listen to the sound and pitch. If an item is hollow, you can test the metal by thumping it and listening to the sound. If you're trying to tell if an instrument is brass or copper, play it. Copper is a softer metal and creates a mellower, rounder sound. Brass has a brighter or slightly higher pitched sound.
Have your item chemically analyzed. There are a variety of ways that a chemist can distinguish copper from brass. You need to make sure that you have a professional analyze it to prevent damage to the metal.
Search for markings on the metal. Brass in the United States is regulated by The Unified Numbering System. Brass items are identified by a code starting with C followed by three to five digits. If you see a code like this, it's most likely brass.