Another practice run... All those teeth, arrgh! 
After looking at this on a lot of different background colors, I had a much better idea of how to get it passably good on transparency, but there's still quite a few teeth that look weird to me...
Note this would be 9 colors, but the smaller gear has its ramp tinted slightly blue... for no reason I can think of other than I am weird and I like it that way.
Any suggestions will be met with great appreciation. :D | 
You could taper off the ends of the gear teeth. It'll make it look more streamlined, and physically it helps gears mesh together with reduced stress. The shading on the metal's pretty good. The polished metal constrasts well with the rougher inner portion of the gear.