Good quality yarn is imperative in crafting fine quality rugs. In rugs, first-grade, pure wools, silk, esp hand-spun yarn is ideal.

How can one identify good wool?

It must have a good lustre or sheen.  It is common to see inferior quality wools mix with manmade materials to fake the sheen of high-quality wool.  This practice is to be avoided as inferior quality wools will become weak and fall apart, and these ecologically-unfriendly manmade fibres are known to attain an odd smell over a period of time, particularly if spread on a heated floor.

Also, the highest quality wools are hand-spun.  This is easily noticed in flat-weave rugs owing to a “knotty” feel to the weaving, but is difficult to identify in hand-knotted rugs.