Domed washers?

I was unpinning an old set of scales yesterday and noticed that there was what looked like 2 washers on the outside of the scales. The one closest to the scales was darker and the one on the outside was shiny.

Both appeared to be rounded or domed. Kinda like a bagel that had been cut in half and then had all of the soft bread inside taken out. Anyone know why this was done (other than aesthetics) and how I can replicate that?

The pins looked like the ones on my Edelweiss (the middle and pivot are the best examples in the following pic):
http://straightrazorpalace.com/membe...cture956-a.jpg

I have only seen this done on vintage pins a few times, mostly on older W&B's, Rodger's and Reynold's razors...
You can duplicate it with using a doming and dapping set, and 2 different size washers... The smaller washers can be put under the larger washer for support. and a clean look. or the other way around for the bullseye look.....