Niccolò is best known, however, as a miniaturist. In addition to his "Assumption" from the "Callefo" in the Siena Archives, that city's library contains an antiphonary with four illuminations by Niccolò (Virgin and Child, Presentation, Baptism, Resurrection of the Dead). The Museo di Arte Sacra in San Gimignano preserves a choirbook (Graduale LXVIII) with a number of historiated initials attributed to Niccolò (Adoration the Magi, Presentation Pentecost, Trinity, Assumption of the Virgin, San Gimignano adored by five monks, San Gimignano Enthroned). The Cini Foundation in Venice has a fine cutting with the Annunciation.
