They're both factory springs.
No one ever made after-market springs for the small frame Colt's, and the only after-market springs I ever saw for the mid-frames were the Trapper light weight springs made in the 70's.
I have no idea when Colt used blackened springs versus bright finished.
I'm going to assume that Colt used the bright springs
earlier, and the blackened springs later.
With that in mind, I'd "assume" that a 1941 model would have the dark spring.