Look for common Persian rug designs. Designs like the parrot, paradise bird, lotus or a variety of other flowers are common to Persian rugs and less common to other areas. Though some flowers and birds are seen in other rug designs, flowers from the Middle East are a sign of Persian rugs because other areas of the world do not commonly have the flower.
Find the location where the rug was made. Inquire about the rug's origin. The dealership selling the rug can determine where it was made and that is a large clue as to whether the rug is Persian or another Oriental rug. Oriental rugs and Persian rugs are similar in materials, but they come from different locations. A Persian rug comes from the Middle East---specifically from Iran---and a rug that comes from any other location, such as India, Pakistan or China, is Oriental.
Pay attention to the materials of the rug. Wool is a common material for Persian rugs, while materials like cotton or other plant-based materials are less common. Any rug that is made from cotton is not a Persian rug.
Look at the knots of the rug. A machine-made rug does not have the same knots as a hand-woven rug. The rugs on a hand-woven Persian rug have two bumps that form a single knot and form patterns that are typically symmetrical. The rug count is determined by counting the knots in the rug and the typical Persian rug will have more knots than other rugs. A quality hand-woven Persian rug will always have more knots than either machine-made rugs or lower-quality rugs.