This 1970s Yves Saint Laurent sweater is from the iconic Rive Gauche ready-to-wear line. Made in Hong Kong, it's black ribbed wool with purple trim. The front fastens with ten toggle buttons and it has a large pocket on each side. 

The sweater appears to have had very little wear, although there are a few repaired moth nibbles. These are only visible under close inspection. There are also a couple of small holes on the inside of the purple trim, which can't be seen when fastened. It has been professionally dry-cleaned and is ready to wear.