Silver with polished & unpolished areas

I am currently working with an object that is silver and I have a convincing silver material, and some nice lighting to go with it.
The only thing really lacking and holding it back from photorealism is an unpolished look to the nooks and crevices. In real life, deeper regions would appear darker and more matte.

Basically I want to “paint on” the regions which are to become the unpolished material in a way that they fade into the polished material. I’m envisioning a process by which I can just paint-on one-color regions which will have alpha transparency and then use the resulting texture to map which regions will become the second (unpolished) material.

Is this making sense to you all? Does anybody out there have advice on how to do such a thing?

Thanks in advance,

one thing you could do is to bake an ambient occlusion map, then use the ambient occlusion map (applied to a separate material) as the value for a mix node that mixes your two materials.

Using what Nebopolis said about occlusion maps you can map them to things like the raymir and spec values to get more realistic results.

Thanks guys.
Sounds like I will have to do some study on AO baking and nodes, as I have not explored those features yet. Googling now…