Bands, buttons, pen parts, coins... if the item is shiny and labelled as nickel, nickel silver, german silver... it is a white bronze, where the nickel content, makes it white. Pure nickel is grey in color, with a black film that can be rubbed off on your finger. It does not hold a polish, and production costs of making something is rather expensive. Pure nickel is usually reserved for jet engine part and racecar engine parts... things that require a substance that can take very high heat, does not create a friction heat, and is very hard. A pure nickel band, wouldn't be very pretty.
I have worked with some pure nickel that I used to build models for producing models of production designs with, but it is a pain to work with. I have to get all hazmat suited up because it is rather toxic and can create allergies when broken down with grinding and sanding, and just a particle of it getting into my silver alloy makes it refuse solders. aggravating. I gave a bunch of it to a friend who builds parts for his high performance engines.
Nickel bronze is mostly a copper based bronze, very cheap. It is electroplated or chemically treated (similar to a galvanization process) to make it keep a shine. It is durable for a long time, but once it has lost that shine, you might buff it back to shiny, but the slight hazy warm color will start to show and it will not keep that shine for long. Then they mail it to me to put a sterling band on it.
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