What color thread
 

Would you use for quilting? Light purple, white, dark purple, what?

How are you quilting it? machine, hand? How confident are you in your quilting skills? Do you want the quilting to be the focal point of this or a background embellishment? I think answering these questions will tell you what color to use.

I will be hand quilting it. Would like for the centers of the blocks and the footballs to show the quilting.

Since you want it to show I would use a medium purple, something just a shade or two darker than the material.

In that case I would go with a light or medium purple. Dark purple may be too detracting and very often dark thread on a white has a tendency to take over. Especially in a solid as is the case in your quilt. I would audition a purple very close in value to the ring colors and maybe a shade lighter like a lilac. Your choice in batting will also impact how much the quilting will show. Something like Hobbs Polydown will give much more relief and shadow to the quilting (thus having it show more) as opposed to something very flat like Quilters Dream select or Hobbs 80/20.

Medium purple would be my choice.

I agree completely with Feline Fanatic. :)
Looking pretty so far!
Jan in VA

Light purple I agree! :) This is beautiful

Hard to tell if my monitor is showing your fabric colors accurately, but I would match the thread to the fabric of your centers/footballs. If this is a light purple, then definitely would use that. You will see the quilting even if it matches the fabric color. Beautiful quilt :)

Christine

i'd use light purple