Losnummer 244. William and Mary (1688‑94), Five Guineas, 1691, conjoined busts right, legend surrounding, GVLIELMVS ET MARIA DEI GRATIA, toothed borders both sides. Rev, crowned quartered shield of arms with scalloped frame, eight strings to Irish harp, Lion of Nassau at centre surrounded by eleven billets, date flanking top crown, reads MAG BR FR ET HIB REX ET REGINA, edge inscription as DECVS ET TVTAMEN ANNO REGNI TERTIO (S.3422; ECG.344; MCE.136). Sandy gold toning with some iridescence around the periphery, the jugate portraits showing strong detail with the usual areas of distortion, few bagmarks, small striking flan flaw in the S of Kings name. Rev, pleasing, the odd annealing metal fissure. Very fine.By the latter end of the 17th century, Isaac Newton's work at the Royal Mint transitioned from that of Warden to Mint‑master and as a man of science, Newton introduced both more control and a more scientific approach to the operations of the Mint modernising it, especially in its striking efficiency. The first 5 guineas issued for William III are noticeably different from the issue of 1701 in that the king's portrait was shallowly engraved. Newton attempted to complete the transition begun during the Renaissance, of departing from the shallow style of portraiture of the monarch to one that suggested lifelike qualities. In 1701 he caused a portrait to be deeply engraved that the mint machinery could sufficiently heavily strike.As Mint‑master, Newton's finest artistic achievement is, without argument, the deeply engraved 5 guineas of 1701, now known as the 'Fine Work' issue, and it has become one of the classics of British numismatics. His mark on English coinage and medals became indelible, and among his medals may be found exquisite images in high relief, but his greatest achievement was certainly the 'fine work' engraving of the king's portrait used in only one year, 1701, on the gold 2 guineas and 5 guineas. These are the ultimate numismatic images of the reign and rarely equalled as works of art in all the years that have followed.