The last of the great jewellers of the Quattrocento was Michelagnolo di Viviano, who worked at Florence under the patronage of Lorenzo and Giuliano de' Medici. He was the earliest instructor of the greatest goldsmith and jeweller of the late Renaissance, Benvenuto Cellini, in whose _Treatise_ and _Life_ he is spoken of with the highest praise. From actual examples we obtain but slight information of the Italian ornaments of the fifteenth century; but that there is a distinct alteration in the style of jewellery between the Quattrocento and the Cinquecento, the pictures of these great artistic periods offer abundant proofs. This difference is particularly noticeable in ornaments for the head. During the fifteenth century we find the forehead heightened, and the space thus obtained emphasised by a single jewel placed at the top of the brow. This form of ornament is admirably shown in Piero della Francesca's "Nativity" in the National Gallery, and particularly in his "Madonna and Child," with saints and angels, and with the donor, Federigo of Montefeltro, Duke of Urbino, in the Brera, Milan. The parts of these two pictures most characteristic of the artist are the figures of the angels, who wear jewels executed with extraordinary brilliancy--compositions of pearls in delicate goldwork enriched with blue enamel. Precious stones and jewels were often sewn, at regular intervals, all round the band of ribbon or galloon that encircled the head, as seen in a portrait in the Ambrosiana, Milan, ascribed to Ambrogio da Predis, and considered to be that of Beatrice d' Este; but it is more usual to find in the centre of the brow an isolated jewel, held by a narrow ribbon or silken cord, knotted at the back of the head--as in Caroto's portrait of the Duchess Elizabeth Gonzaga in the Uffizi, who wears on the forehead a jewelled scorpion, emblem of logic.