Gloria,
Converge means to "come together from different directions so as eventually to meet." I've used 4 different fabrics on this quilt and "made them come together." :lol: I made one convergence quilt where the fabrics were very similar so you don't have to have contrast at all. It's all up to you the designer.
You can learn more about convergence quilts from Ricky Tims at
http://www.rickytims.com/
Have fun!