This is a unique way to show off lace curtains. The top fabric can be an off white such as this, a different color lace, a print fabric or can be a solid color brought in from accents in the room. The pleating is called "Ripple Fold"
White Tulle Sheer and Light Blocking Combo Beautiful and so much like the waterfall look I'd want. Layer white tulle over solid blue curtains on a curved shower curtain. Potentially layer multiple shades of tulle and/or use an iridescent base fabric?