Watch List notes:

Papal States. Sixtus V. 1585-1590. BI 6 blancs (27 mm, 4.06 g, 2 h). Carpntras mint, Extremely rare. Large S surmounted by tiara / Cross fleurdelisée. Berman 1392. Fine, crude as issued. 

Berman does not include a valuation for this coin, noting that it is extremely rare (RRR).