The fakes or reproductions that are generally encountered originate in Mexico, Ukraine, India and Pakistan with a few forgeries made in the United States. The fake rugs from Mexico are woven on a horizontal Spanish/European style loom. The warps are attached to the loom at each end. There may be a cabled bundle of warps at each side to provide dimensional stability during weaving but there will be no side cords as in a genuine Navajo rug. When the rug is finished, it is detached from the loom and will now have the warp ends dangling from each end. To fake a Navajo rug it is now necessary to darn the ends back into the body of the rug. While doing this, a non functional set of end cords is applied. Side cords might also be attached in order to complete the fake.
The easiest and most foolproof way to determine a fake Navajo rug is by examining the ends to see if the warps were tucked back in or if they are truly continuous. If they are tucked in, then every other warp area will have two threads as is illustrated below:
If there is a bundle of warps at the edge of each side, then it is unlikely that the rug is genuine. Very few Navajo rugs will have such bundles and even then there would be only two or three warp threads that would make up that bundle and there would be only a single warp thread next to that bundle. Most Navajo rugs have side cords as I described and virtually no Navajo rugs have warp thread fringe at both ends.
Section Lines
Many Navajo rugs will have what Indian arts dealers call, "lazy lines." It is an inaccurate and insulting term that I hope will be replaced by the term, "Section Line." The section line line is a diagonal joint or break in the weave where a weaver has worked on a single section of the rug without having to reach all the way across the rug. She weaves one section, then moves over and weaves another section. This creates the diagonal section line. Not all Navajo rugs have section lines.
End Borders
The end borders in Mexican imitation Navajo rugs are generally much wider than in a genuine Navajo rug. Side borders are often wider as well.
End finishes
If the rug has fringe at both ends that are extensions of the warps, then it is not a genuine Navajo rug.
Materials
Wool is the standard material used in the making of a Navajo rug. There are a few genuine Navajo rugs made using synthetic materials such as acrylic. If encountering one, it could be looked at as the result of a Navajo woman weaving her own cheap knock-off. In such case, it probably doesn't matter is it is real or not.
The imitators may use wool but there are poor fakes made in Mexico that use polyester. Some fakes made in India or Pakistan use a blend of wool and polyester or acrylic. Contrary to another author, sniffing the rug to determine if the rug is made from wool is not useful. Much of the wool use in contemporary Navajo rugs has very little lanolin and doesn't smell at all. Older rugs may have been cleaned or have acquired other odors. It is comic to watch a potential buyer go through a store's inventory sniffing the rugs. A buyer should learn to distinguish the look and feel of wool from other materials. While there are more scientific means of testing for wool, they are usually not practical in the context of purchasing a rug from a store or Indian arts dealer.
Mexican Rugs
Zapotec and other Mexican knock-offs often have wide end borders and end cords that are added after the rug is woven. The warp ends will be buried along side the adjacent cut warp ends as described previously. It should be noted that many knock-offs, regardless of origin, use designs taken directly from photos in books. The Zapotec are the #1 makers of counterfeit Navajo rugs. In Teotitlan de Valle (Zapotec rugs) much of their entire industry is devoted to making fakes and knock-offs. They make the hightest number and most convincing fakes.
Ukraine Rugs
Rugs woven in the Ukraine will be good reproductions of Navajo rug designs. The sides selvages have bundled warps and the ends will be nicely hand serged. These rugs are really flatwoven rugs with southwestern or Navajo style designs. Unfortunately they are often sold as the genuine article in Indian arts stores.
India & Pakistani Rugs
The majority of these fakes are really just dhurries in Navajo rug designs. Some of the better fakes use good quality wool or a wool and polyester blend. Some really bad ones use polyester yarn. Dhurries are very cheap even in the more intricate patterns. The sides selvages have bundled warps and the ends will be hand serged.
There is a company that has a line of more convincing fakes made in India. They sell these rugs as "inspired by Navajo rug weaving traditions" and are an attempt "to reproduce the exact feel, texture, weave and look of the Navajo hand-woven rug." Their tag line is, "The Most Authentic Reproductions Based on the Navajo Weaving Tradition." These bogus Navajo rugs are complete with side cords, section lines and end finishes that can fool you because they are very convincing.
American Rugs
Any handmade imitation Navajo rug made in the United States would probably be woven with the firm intentions of deceiving the buyer. There would hardly be any other reason for a American non-Indian to put in the time and effort required to weave a convincing fake. Because of the economics and the work required, there are very few US made fake Navajo rugs.