Polishing the springs is great, but not really necessary. All you need is bright steel so you can see the colours well. So take your hardened spring and some 180 grit abrasive cloth or paper, and polish off the scale left after the hardening process. Be careful - don't drop it or flex it. It should be hard like glass, and will shatter if abused. then draw the temper. I leave 'em with the lovely blue colour after tempering.