The red is the latest version of the Spin Milled, the black were pre-2010 I think and the gold is the C-C (tournament approved) grooves because of the USGA rule change.  Hope this helps. 

Very nice catch!  Not many ask this question.  They are bounce designations:

White is the high bounce.

Red is the middle bounce.

Black is the low bounce.

RC

Ryan,

You would definitely know before me probably but where are did you find that out?  I looked at all the photos on the Titleist page and all of the current Spin Milled have the red logo regardless of bounce and the C-C versions are all gold regardless of bounce.  Just curious because I didn't know the colors designated that.  Thanks for any info you can give!!!

Steve

I guess I just "know" having worked with them over the years.  The actual loft and bounce on the back is where the color change lies.

Ahhh, I see, I thought he was asking about the actual Saw logo on the back.  That is great info, thanks for sharing!!!

Steve

Interesting... Never noticed this on my Vokeys.

Thank you all, was told at a shop that the color was for the manufacturing year but after browsing thru the Vokey page suspected that the color had to do with the bounce but there was no definite answer anywhere to be found until asking here.