Most of the time you can recognize if the rug has silk pile or silk highlights simply by its brilliant look and silky touch. It is more difficult to determine if the foundation of the rug is made of silk because the threads of the foundation are thin and twisted, and not always easy to differentiate from cotton. In this case you can resort to a test by fire: pull a small thread from the fringe and light a match to it; cotton would burn slowly like a candle wick, whereas silk would crumple and burn like hair with a smell of burnt hair. If the thread actually melts and gives an odor of burnt plastic, then the silk is probably synthetic.
Since silk is more expensive than wool or cotton, the more silk is used in a Persian rug the more expensive the Persian rug. As a rule of thumb the value of a 100% silk Persian rug or Oriental silk rug is twice as much as a wool rug. Otherwise a silk rug depends on the same factors, such as condition, and rarity, as wool rugs.
Silk is used in Oriental rugs in many ways. It is often used, for instance in Nain and Tabriz rugs, to highlight elements of the rug, such as leaves or flowers or their contour. Alternatively, the whole pile could be made of silk, while the foundation of the rug is left in cotton for sturdiness. Conversely, the foundation could be in silk to allow much tighter weaving, while the pile is of wool. Finally, both the pile and the foundation could be in silk. The latter type of silk rugs are usually intended to hang on the wall or to lay down in a space where it would not be stepped on.
Most important weaving centers have produced both wool and silk rugs in the past. Thus you can find antique silk Tabriz, silk Kashan, silk Heriz, Nain, Chinese, Turkish, etc. This is not surprising, since all one needs is switch the yarn to produce either type of rug. On the other hand, village silk rugs are more rare and tribal rugs rarer, as village and tribal weavers rely on locally produced wool, and silk is usually not accessible to them.
The following is a short guide on Oriental silk rugs. Please contact us if you wish to sell a silk rug.