From their website:
Assembly of 3 twisted strands of intense brilliance.
In sewing, it is an excellent thread, very resistant to make stitching on fabrics and leathers, sew buttons and make buttonholes. Perfect on linen 12 or 14 threads per cm, ideal on old canvas a little thin, Pearl silk is also used in traditional embroidery, counted stitch, cross stitch on linen and silk, hardanger.
Tinted in fleets (skeins) to guarantee perfect unison, it is then presented in coil of 16 m and 80 m.
In 1890, the Pearl Silk card had 2688 different colors divided into 107 ranges. It is this card that serves as a reference to add new colors. Our current map of more than 290 colors is extracted from it.