Probably Southern Italian, 15th century

Overall, the condition of the marble is good, with minor dirt and wear to the surface consistent with age. There are a few chips, including to the diagonal fold of drapery at the centre, to the drapery below the proper left arm, and to the bottom edge. There is a larger chip to the drapery on the proper right side of the Virgin. There is some rubbing to the polychromy, particularly at the high points, and the paint has flaked slightly in areas, including to the Virgins hair at the neck.
"In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective, qualified opinion. Prospective buyers should also refer to any Important Notices regarding this sale, which are printed in the Sale Catalogue.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING A LOT, ALL LOTS ARE OFFERED AND SOLD AS IS" IN ACCORDANCE WITH THE CONDITIONS OF BUSINESS PRINTED IN THE SALE CATALOGUE."

The present charming group of the Virgin and Child is reminiscent of the Madonna and Child in the church of Our Lady of Trapani on Sicily: the Christ Child's proper right hand on his Mother's chest, his upwards gaze and their connected hands are apparent in both works. Perhaps influenced by this famous votive statue attributed to Nino Pisano (circa 1349-1386), the present Virgin and Child is of later date, but can probably be attributed to the same region. 

RELATED LITERATURE
J. Poeschke, Die Skulptur des Mittelalters in Italien - Band 2: Gotik, Munich, 2000, pp. 173-175, figs. 152, 153