One of the biggest mistakes I have seen in the Oriental rug world is the misnaming of prayer rugs. Prayer rugs are not the only type of rug that can be wrongly identified, but they are one of the most popular. All it takes is one rug dealer to call something by another name to their customers and before you know it that incorrect nomenclature spreads rapidly.
A prayer rug is characterized by a mihrab design at one end. The mihrab resembles an archway as seen in the photo above. If a rug does not have this niche then it is not, by definition, a prayer rug. Some rugs have a mihrab at both ends, which is defined as a double prayer design. This design is seen in older antique Caucasian rugs.
The field of a prayer rug is most commonly open with no designs and filled with a solid color such as blue or red. The field of prayer rugs can also be filled with designs. The prayer rug below is filled with a paradise design. This type of design usually consists of paradise birds, perhaps the tree of life, and other animals coexhisting. Do not mistake this design for the Hunting design which consists of animals being hunted by other animals or people.
The rug below is filled with an all-over floral pattern and does not include animal figures.
The size of an Oriental rug does not determine whether or not it is a prayer rug although prayer rugs are generally smaller than 5’x7′. If a rug is small, such as 2’x3′ or 3’x5′ it does not mean it is a prayer rug. I have seen many Persian Hamadan mats called prayer rugs when they are not. Below is one of the most common misnamed prayer rugs. See how it does not have the characteristic mihrab at either end.
Some prayer rugs will also have hand motifs which flank the mihrab at the top. The antique Caucasian rug below has two geometric motifs where the hands are often observed.