Natural dyes are dyes made from the natural world, including plants, insects, and sea life. Until approximately 1860, carpets in Iran were made entirely of naturally dyed fibers.

When natural dyes, an organic element, are combined with another organic element, wool, the result is a color that will never be constant. Over time, the dyes in these rugs will change and mature; morphing into beautiful, sophisticated tones that can only be achieved with age.

In the late 19th century, aniline- or synthetic- dyes were introduced through Europe and weavers were often tempted into using them, as they saved countless hours of forgaging for and processing plants and other ingredients in order to produce the large vats of vegetable dyes.

Aside from their convenience, synthetic dyes are inorganic, and thus when combined with organic wool, the resulting color is so much more predictable. In some rugs, this constancy comes at a price- for example the gorgeous shades of red resulting from natural dyes may be replaced with an electric red that lacks character and depth. However, synthetic dyes are nearly always used in city-woven silks and wool-and-silks in which the artist is seeking symmetry, constancy, and perfection. 

In the world of natural and synthetic dyes, one is not "better" than the other- they're just different. You can't beat an antique madder or cochineal red, but a natural "black" turkoman dye can be much more corrosive to the wool than a black synthetic, and a silk Qom demands an on-point color that a tribal does not. Ultimately, a rug should speak to you, and if it achieves this goal, whatever dyes were used, whether natural or aniline, must have been well thought out and carefully chosen by the artist.

Synthetic dyes on a wool and silk Tabriz                Natural dyes on a tribal Turkoman