Sig Sauer Hammer Color: What Causes the Purple Discoloration?

Question
Why do some Sig Sauer gun's have a purple or plumb colored hammer?  Does
this characteristic affect the value of the gun?

Answer
cj,

To the best of my knowledge the discoloration (for lack of a better term) of some individual part/pieces of some firearms is nothing more than a bi-product of the heat treating/tempering processes and I wouldn't worry too much about it.

I should have no effect that I'm aware of on the value of said firearm.

Thanks for the question cj.
Sid Lark