I completed the top of a Mardi Gras table runner. What color thread would you use to quilt it? The backing is purple. Should I use purple as the bottom thread?

I try and use threads that will work on the top and bottom. I do not like to have to keep fiddling with the tension.
There are beautiful varigateds that would be pretty on this runner :D:D:D

What quilting are you going to do - that will help decide on your thread colour. Regarding the backing - I usually try to match my thread to the backing colour, although I make sure it is the same make of thread as the top.

I will sid since at this time that is all I know how to do! Just a beginner!

I would use purple for the back and then depending on the type of quilting I wold change the color of the tope thread to match the section I am working on. But I am not an expert.

In that case why not use invisible thread or if you don't like using it I'd go for a match on the design - eg yellow for those bits and a purple for the rest. Your runner looks lovely - love your colours.

I agree with Amma - about the variegated thread. I use this a lot and like the results.

Either purple or yellow, perhaps green in the green blocks or go with a variegated. You might not be able to find a variegated with purple and yellow in it tho. Check out Superior Threads, I know they have lots of variegated threads in their King Tut line.

I second that.

I'd go with sparkly since gaudy doesn't really work here :)