Lewis & Short

mango, ōnis, m. [μάγγανον], a dealer, monger in slaves or wares, to which he tries to give an appearance of greater value, by adorning them (post-Aug.): mangones quicquid est quod displiceat, aliquo lenocinio abscondunt, etc., Sen. Ep. 80, 9: milia pro puero centum me mango poposcit, Mart. 1, 58, 1: non puer avari sectus arte mangonis, Virilitatis damna maeret ereptae, id. 9, 7, 4; Plin. 24, 6, 22, § 36: mangones, qui colorem fuco mentiuntur, Quint. 2, 15, 25: non a mangone petitus quisquam erit, Juv. 11, 147.
Also, a furbisher, polisher, etc.: gemmarum, Plin. 37, 13, 76, § 200; 12, 20, 43, § 98; 23, 1, 22, § 40; cf. Sillig. ad Plin. 34, 8, 19, § 79.