1.  virtu(n = noun.cognition) connoisseurship, vertu - love of or taste for fine objects of art;
is a kind of appreciation, discernment, perceptiveness, taste

2.  virtu(n = noun.attribute) vertu - artistic quality;
is a kind of quality

3.  virtu(n = noun.artifact) - objet d'art collectively (especially fine antiques);
is a kind of art object, objet d'art, piece

   A love of the fine arts; a taste for curiosities. J. Spence. [1913 Webster]
"I had thoughts, in my chambers to place it in view,
To be shown to my friends as a piece of virtù." [1913 Webster]

virtu, n. (also vertu)
1 a knowledge of or expertise in the fine arts.
2 virtuosity.

Idiom:
article (or object) of virtu an article interesting because of its workmanship, antiquity, rarity, etc.

Etymology:
It. virt{ugrave} VIRTUE, virtu

N  taste, good taste, refined taste, cultivated taste, delicacy, refinement, fine feeling, gust, gusto, tact, finesse, nicety, to prepon, polish, elegance, grace, judgment, discernment, dilettantism, dilettanteism, virtu, fine art, culture, cultivation, aesthetics, man of taste, connoisseur, judge, critic, conoscente, virtuoso, amateur, dilettante, Aristarchus, Corinthian, arbiter elegantiarum, stagirite, euphemist, caviare to the general, in good taste, cute, tasteful, tasty, unaffected, pure, chaste, classical, attic, cultivated, refined, dainty, esthetic, aesthetic, artistic, elegant, euphemistic, to one's taste, to one's mind, after one's fancy, comme il faut, tire a quatre epingles, elegantly, nihil tetigit quod non ornavit, chacun a son gout, oculi pictura tenentur aures cantibus, taste, flavor, gust, gusto, savor, gout, relish, sapor, sapidity, twang, smack, smatch, aftertaste, tang, tasting, degustation, gustation, palate, tongue, tooth, stomach, sapid, saporific, gustable, gustatory, gustful, strong, gamy, palatable.