627 is a grey from the Au Ver à Soie Soie 1003 range: a spun (combed) silk made of 3 twisted plies, with a moderate lustre. It suits all kinds of needlework and is at its best in traditional embroidery and fine cross stitch, where the fine, even thread gives crisp stitches.
The palette has about 290 colours, drawn from the historic 1890 Au Ver à Soie shade card like those of Soie Perlée and Surfine, which share the same numbers. Photographs do not always match the real colour: for an accurate match use a shade card.