It starts with the raw casting. That nub you see on the bottom is where the sprue for casting is attached.

The first step is to file away the sprue... 
...until it is even and smooth with the rest of the surface.
Then I sand down the rest of the sections starting with a course grit, up to a fine grit. At this point, it is almost to a shiny polish.

Finally, to get that soft brushed texture, I use this polishing wheel and gently press the casting against it as it's spinning.

Last but not least, I create the chain and assemble it to the pendant.