Though a sense of surface frigidity characterises everything Bronzino produced, emotional heat underwrites his style. As a pupil and adopted son of perhaps the greatest and strangest of mannerist painters, Jacopo Pontormo, Bronzino graduated to artistic maturity with impeccable credentials in that consciously artificial style. That he asserted his own artistic personality, albeit through a steely formality of technique, testifies to the originality of Bronzino's vision. In this magnificent portrait of his principal patron - a work that exists in many replicas and copies - the painter displays a perfectionism it is hard not to think obsessive. Riven with reflections, highlights and shadows, Cosimo's armour alone is an article of transfixing interest: almost reason enough for the painting. It was Bronzino's habit to concentrate on details of costume, jewellery and decoration, to the extent of conceiving the faces of his ducal sitters as polished stones. Apart from this authoritative example, another celebrated version of the work is found in the Uffizi Gallery in Florence.
AGNSW Handbook, 1999.