"Tuscan School" closely follows a Sano di Pietro example

Boetto, Italian auctioneer, sells on 29 September 2015 a "Tuscan School, golden background triptych" with a Virgin and Child, Saint Jerome (left) and Saint Bernard of Siena (right). Medium-sized at 67 by 71 cm, it is estimated at 4,500 to 5,000 Euro.

It is a rather crudely painted, reasonably well-preserved typical work, and seems to be inspired quite heavily by the work of Sano di Pietro, although completely lacking its refinement. A work from ca. 1465-1470, from the Museum of Siena, is very similar for the central panel, has swapped the Bernard to the left side, and has replaced Jerome with Saint Catherine.

The Saint Bernard is relatvely generic, but the Madonna is much more telling. The position of the Virgin and Child, down to many details, plus the drapery in the background, the curved round pillow on the chair, all point to a common origin. The most logical explanation, considering the difference in quality, is that the work for sale is a copy after Sano di Pietro (this work or a similar one, many di Pietros use the same elements). Being a late (post 1465), poor copy, the estimate seems rather high, even though these kind of triptychs don't turn up that often any more.

UPDATE: not sold, the estimate was indeed too high.