You are right, well spotted! It looks like a 12 sided one.

Partly blued got my vote. The idea can be expanded to color coding, like screws to mainplate one color, another color for ratchet or winding wheel. Though I wonder what aestatic effect would multicolored have, perhaps unsightly.

My 508 only has an amplitude of about 190 after cleaning and oiling. All play is good. What could this be?

Hello all, I've just opened up a Citizen non-runner I picked up on eBay. Miyota 8200A movement. Seller reported snapped stem only. However I noticed the hairspring was way out of alignment, so took a closer look. Behold:   This is totally wrong, no? It seems to double back on itself, as if someone has tried to install in upside down and just bent it back through the regulator? I'm a novice and would appreciate any insights into this. How could it have happened?     Thanks in advance,   Sam

They're hard to see although maybe there in my imagination? To be honest I didn't see them originally I was trying to figure out how to pry the back off to get the battery in but I was pondering the strap which is not the usual found on a battery watch because it looks vintage. Then if you go back and look carefully you can see the ring and its facets and it looks like somebody's been trying to pry the back off.