Hi, Mary.
If I am remembering that episode correctly, it was a session with Evelyn Sloppy, highlighting one of the quilts in her "Strips and Strings" book (published by That Patchwork Place).
The quilt is called "Tranquil Treasures" and is the reason I purchased the book, although that was a while ago and I still haven't made the quilt.
The way the values move from light in the center to darker at the outside does indeed make the quilt seem luminous.
Hope this helps.
Robin