But the glory of Northern European stained glass came to an end with the Reformation. Protestant iconoclasm was responsible for the destruction of much northern European religious art, including stained glass, though the ravages were somewhat selective. "Stained glass windows had an unusually high survival rate based on local whims," Shepherd explains. "Some religious subjects, like the mystical incarnations of the Virgin Mary, were taboo in Great Britain, but other straightforward biblical subjects were fine. The Dutch were ruthless in the oppression and destruction of religious stained glass in their churches, and to this date almost no medieval stained glass from Holland survives." Even worse destruction and dispersal occurred during the French Revolution and the Napoleonic invasions. Just as many French royal Baroque and Renaissance tapestries were burned to retrieve the gold threading, many windows across France and Germany were dismembered for the leading, which was reused for cannons and bullets.

It was only with the rise of the Romantic movement in art and literature and the fascination with the "Gothick" early in the 19th century that medieval and Renaissance stained glass was appreciated anew, particularly in Great Britain. Eccentric collectors such as Sir Hans Soane sought out sections and fragments of windows as much for their lustrous colors as for their ancient charm. "Pieces of old stained glass were often found littering churchyards," notes London dealer Sam Fogg, "and many 19th-century collectors fitted them together with new pieces of glass to make new windows, sometimes completing a figure or, more interestingly, making a composite window where heads, foliage and other details are arranged artistically between colored or clear modern glass."
 
As stained glass became a fashionable accessory in many a Victorian manor house or chapel, older panels were often extensively augmented with newer glass. "It’s almost impossible to tell from a photograph if a piece of glass is old or new," says Timothy Husband, curator of medieval art at the Metropolitan Museum of Art. "You have to see it with your fingers; the surface of the glass will tell you how old it is. Older glass often has a very irregular surface, while newer glass tends to be smoother and thinner."
 
Two of the most important collections of medieval stained glass owned by Americans were formed by J. Pierpont Morgan and Henry Walters. Though much of Morgan’s medieval art collection was donated to the Metropolitan Museum of Art, he kept his stained glass in London, and it was donated after his death to the Victoria and Albert Museum by his son in an effort to offset estate taxes. Walters’ collection, now in the gallery that bears his name in Baltimore, was found after his death, still crated and unopened.

The most assiduous and devoted American collector of medieval stained glass was Raymond Pitcairn, heir to the Pittsburgh Plate Glass Company fortune. A devout Swedenborgian, he oversaw the construction of the Swedenborgian Cathedral in Bryn Athyn, Pennsylvania, about 15 miles north of downtown Philadelphia, from 1915 to 1919. To aid the workers, Pitcairn bought some medieval glass panels as models, but soon became enamored of them as works of art and eventually purchased more than 250 panels for his own Romanesque-style home, "Glencairn," built in the 1920s.

Though many American museums have some excellent examples of stained glass, the finest and most varied collection is in the Metropolitan Museum of Art and in the Cloisters, atop Fort Tryon Park in upper Manhattan. Stained glass is a particular interest of the Cloisters’ curator; in 1995, Husband presented "The Luminous Image," a landmark exhibition of early 16th-century Netherlandish roundels, and he has been instrumental in upgrading the Metropolitan’s collection in all areas of glass. He is always on the lookout for more silver-stained roundels, and recently added two of particular beauty: a fine Flemish roundel of "The Assumption of Mary of Egypt" and a North Netherlandish roundel depicting "Sorgheloos in Poverty."