What is this bandsaw finish?

I have received a sample piece of material, but am having a little diffulty in determining what or how the yellow (or gold) color was achieved. The material is Carbon Steel (I do not know the carbon content). My guess is a controlled preheat, but I thought maybe someone out there may have a better synapses.

Any ideas?

First of two simultaneous responses --

You can see where the teeth have been hardened with heat, so the tint is probably from the temper cycle after the heat treat. Probably just oxides and possibly a little trace of burned cutting fluid.

Second of two simultaneous responses --

It could be a TiN coating -- at least it looks like TiN in the picture. If it is, you should be able to tell. TiN is very hard, so the surface should not scratch very easily.