When is a lamp not a lamp? When it's a Tiffany lamp, in which case it qualifies as a work of art. By the end of the 1970s, the lamps of American art nouveau designer Louis Comfort Tiffany, son of Tiffany and Co. cofounder Charles, were fetching up to and beyond $100,000 apiece at auction, thereby confirming that dealers and collectors, at least, considered them art. The market for Tiffany originals has since fluctuated, but the classic Tiffany lamp has never really gone out of style. Thirty of these exquisite creations are currently on view at the Boca Raton Museum of Art in "Tiffany Studios: The Holtzman Collection." A vibrant little show, it includes not only lamps but a complement of vases, desk sets, and other items from Tiffany Studios, which had its heyday between 1902 and 1938. The works come from the collection of Evelyn and Seymour Holtzman, who bought their first Tiffany lamp in the late 1970s or early 1980s — the exhibition catalog mentions conflicting dates — and have since amassed one of the largest private collections in the world. (A photograph of their Tiffany-studded Palm Beach sitting room is enough to make you drool.) The Boca Raton's presentation of these stained-glass wonders comes across as a bit slapdash, but the lamps themselves remain magical enough to compensate for the shaky showmanship. (Through April 27 at the Boca Raton Museum of Art, 501 Plaza Real, Mizner Park, Boca Raton. Call 561-392-2500.)