Watercolours is a three-ply pima cotton - a long-staple, extremely strong fiber. It is mercerized, which makes it even stronger and gives it it's characteristic sheen. Watercolours is not a pearl cotton. Pearl refers to the twist of the yarn, not the type of fiber. The three strands are cabled, but are divisible. They should be separated even if working with multiple plies so that you can control the smoothness of your stitching. Watercolours has the same versatility as Persian wool and can be used for all forms of needlework including needlepoint, cross stitch, tatting, hardanger, darning patterns, knitting, crochet, and crewel.