A little-known fragment of cross-slab from St Ringan's Cairn in the Grampian Mountains of Aberdeenshire is identified as a significant example of Pictish sculptural art of the late 8th or early 9th centuries. It was created by a skilled stone carver with an exceptional sense of design, probably based in a monastery in southern Aberdeenshire or Angus, and its location marked an important route through the mountains between north and south Pictland.At a seminar on Scotland's early medieval sculpture held in 2003, Isabel Henderson drew attention to several fragmentary carved stones which she termed 'fragments of significance'. 3 These indicate evidence of quality of design and carving, knowledge of art styles used in manuscripts and high-status metalwork, and communication of ideas between north and south Pictland. 4 The purpose of this paper is partly to add another fragment to this select group of significant pieces and to show how it fits into their criteria of excellence. In addition, the provenance of the cross-slab allows conjecture about its function and about the location of the stone-carving workshop that produced it. The author's attention was drawn to the cross-slab and socket stone from St Ringan's Cairn by the publication in 2007 of John Borland's drawings, which show the very high quality of carving displayed by the fragment of what must once have been an impressive cross-slab. 5 Although the carved stones were discovered in 1964, they were not recorded accurately until 2005, when the Royal Commission on the Ancient and Historical Monuments of Scotland drew them in the University of Aberdeen Museums and Collections in Marischal College. St Ringan's Cairn lay on the 320m contour just below the crest of Redstone Hill, which is a spur dropping south-south-east from Cairn