NuGold is an alloy of copper and zinc and it will naturally tarnish when exposed to oxygen, like all copper based metals. ... The tarnish is actually a protective coating for the brass, but if you prefer the shine of new, it is easy to do by tumbling or using some common household products if you don't have a tumbler.

Will brass turn your skin green?

It might. It is the copper in brass and bronze that might cause your skin to turn green, and this likelihood is increased if your jewelry comes in contact with water. As such, if you're wearing a brass ring, it is most likely to leave a green mark on your skin when you sweat or wash your hands.

Does brass discolour?

Since brass is usually made of a combination of zinc and copper, it can often tarnish, or oxidize - leaving you unwillingly green with envy. This is because the oils in your skin, the air's oxygen, and even the humidity level outside all combine to make a perfect storm in the brass.