Guillaume Courtois (Guglielmo Cortese) (after) ( 1628 - 1679 ) was a painter. Guillaume Courtois (Guglielmo Cortese) (after) s works have been auctioned off multiple times, with realized prices varying according to the size and medium of the artwork, for instance of 1003.53 USD for Portrait of a gentleman, bust-length, in black costume with a white lace collar in 2017