Persian city rugs from Isfahan in central Iran, among the most finely knotted anywhere: usually 500-700 KPSI (roughly 7,750-10,850 knots per 10 x 10 cm), second only to Qum. Most are woven in fine kork wool from young sheep; some have a silk-and-wool pile on a silk or cotton foundation, and a few are reportedly pure silk. Designs draw on nature and the city's architecture, from medallion-and-corner and floral allover layouts to hunting scenes, trees of life, prayer niches and pictorial gardens, usually in soft pastels with indigo and bright red on an ivory ground. Most pieces are signed, and large sizes are scarce and costly.
A rug whose pile is entirely silk, woven on a cotton foundation or on a silk foundation; when both are silk, no wool enters the rug. Silk's fineness allows the highest knot density of any Persian rug, roughly 600 to 1,000 knots per square inch (about 9,300 to 15,500 per 10 x 10 cm), so the pile is kept low to show the design, and the fibers give a luminous sheen that shifts with the light. About 90 percent of Qum rugs are silk on both foundation and pile, as are some Isfahan rugs. These are the most expensive Persian rugs; they are delicate and stains are hard to remove, so they suit display, formal rooms or wall hanging rather than dining rooms or homes with pets.
The name of a weaver or workshop woven into a rug, either in a small framed box (a cartouche) or directly into the border stripes. It works as a maker's mark that ties the rug to that workshop's standards; signed pieces from famous workshops sell for more and are sought by collectors, and a rug sold under a workshop's signature must truly come from that workshop. Not every workshop rug is signed, and a workshop can stop using its signature. Isfahan rugs and newer Qum rugs usually carry one, while most Nain rugs, silk-foundation Yomut Turkoman rugs and many older Qum rugs do not.
The Isfahan workshop founded in 1940 by Haj Agha Reza Seirafian, a banker who had long traded and produced carpets, and carried on by his family through several generations. It is widely regarded as the best-known name in fine Isfahan rugs, which are densely knotted in fine wool, sometimes with silk, in floral and medallion designs. As in other elite city workshops, the master's name is woven into a border or a small cartouche, which ties the rug to the workshop's strict standards and makes signed pieces sought after by collectors.