Starting with a raw brass piece that is very shiny.
Pour the ammonia in the little cup and place it the container and your pieces of raw brass. Do not overlap the raw brass and make sure the ammonia does not spill on the pieces. Lock everything in the container and wait overnight or most of the day until it turns dark black and green.
They will look dark like this. Shine the pieces with a dremel tool using the carbon steel wheel brush. The brush has silver bristles.
After it is shined you will get a lovely brown tone and shiny surface.
You can also buy your pieces already oxidized brass and oxidized silver. Oxidized Sterling Silver is a little more expensive then the brass because it is sterling silver and the depending on the silver prices.
You will find all of my hand made antique button jewelry in my (ETSY SHOP). So stop by and take a look at my creations.