The first crease color I ever learned to make was a mix of pyrole red 05, burnt umber, and pyrole red 02 (or Genesis red would work).
The next color I learned was “dirty purple” which is pyrole red 02, ultramarine blue, and Genesis red.
Now I do creases in 3 or 4 layers
Layer 1: pinky purple- dioxide purple with a bit of pink and if too dark white
Layer 2: dirty purple but on the red side
Layer 3: blushing color
Layer 4: I use a blushing+black or brown for deep creases (like between fingers, or deep folds)