I started with a black primer from Scale 75.
After the primer is well dry start drybrushing with a big brush a dull metallic paint. I used Black Metal from Scale 75 for this step. Dont go too dry as you need a well coverage of the first layer.
Keep adding more layers of drybrush with brighter metals. I used Gunmetal from Model Air and Heavy Metal from Scale 75.
When everything is very well dry keep a pencil with a heavy tip, something like an H pencil and make random patches over the paint. After that buff it with a paper towel to get a bare metal look.
For the leather I used a base coat of Red Leather from Vallejo which I wetblended with Black from Vallejo and made random patches of paint while everything was wet.
When everything is dry apply random washes of dark colors. I used Nuln Oil and Agrax Earthshade to get random patches of paint. I drybrushed the whole zone to highlight the texture with a mix of Red Leather and Suuny Skintone from Vallejo.
If you need more saturation or color variation you can add thin glazes of different inks. Chestnut and Wood from Scale 75 work wonders for this.
Work the other metals. For the golden ring I used Dwarven Gold from Scale 75 and Gunmetal from Model Air for the inner part.
Now its time to weather the metal. I used pigments for this but you can do it with washes too. I picked rust and earth pigments from AMMO and start making patches of pigments on lower areas. Also work on reccesses and points where dirt and rust would naturally deposit.
If you don't have pigments do the same with very controlled patches of washes on the same areas.
If you see ugly patches or wrong deposits you can remove them with a little bit of alcohol and a small brush.