Copper Or Brass

Hello! New, here. I have an 1859 large cent that I bought about 30 years ago, advertised as a brass strike curio. Don't worry, I didn't pay much--at the time, the brass strikes were mentioned, but not listed, in Charlton's. A few years ago, a dealer said he didn't think it was brass, though he hesitated when he saw the yellow highlights on the reverse. (See the uploaded photo.) He suggested checking the color of the fresh metal by making a small scratch on the edge with something non-metallic. I'm still searching the house for a diamond big enough!

Cheers -- John