Etymology (from OED online): < Anglo-Norman and Old French vert de Grece (c1170), Old French verte grez (13th cent.), vert de grice (1314), vert-de-gris (15th cent.; also modern French), lit. ‘green of Greece’: see vert n.1 Compare medieval Latin viride grecum (14–15th cent.). The terminal syllable at an early date was no longer understood and hence underwent various corruptions of spelling and pronunciation.

NB: note earlier dates