Metal plating tips-on the various watch displays

In the production of watch display , the metal is more and more important  because metal can have good display and increase the high-end . what is the different of Zinc ,nickel and chrome ??

1) Color : Zinc is white without any glossy , nickel is silver and glossy and chrome is white and glossy 

2)Price :Zinc is the cheapest , Nickel is middle and chrome is the most expensive 

3) Rust resistance: Zinc is bad , Nickel is better and chrome is the best .