Passivation of 420 Stainless Steel and Color Changes

I use both carbon ball bearings and 420 stainless steel ball bearings in my factory. To prevent the factory workers from confusing the carbon balls abd the SS balls, I want to change the color of the balls enough to recognize the difference between the two. The 420 SS balls are passivated because I need 72 hours salt-spray corrosion resistance. Can the passivation process be used to change the color of the SS balls enough to make them easily identifiable? If not, what other low cost method can be used to change the color, or to help differential the SS balls from the carbon balls in the factory? Given the much higher cost of the SS balls, I don't want the factory workers to accidentally use them inappropriately.

Thanks for the help!

The cheapest way to distinguish between two types of stainless alloy types is to select magnet which will hold carbon ball, but will not hold 420-ss ball.

We have special passivating process for different high-carbon and 400-series alloy types. We can test these balls and see if there will be color difference between different alloy types.