1. Always refer to a rug size listing width first. A rug measuring 3'x5' should always be referred to in size with the smaller number first (usually the width), then the larger (usually the length).
2. Refer to a rug as "antique" if it is at least 100 years or older. The statement of a rug being an antique for pieces over 100 years reflects a more modest approach, which is a nod to an old internationally accepted customs law. To this day, most museums, reputable sellers and collectors alike will only consider an oriental rug as being "antique" if it is in fact 100 years or older.
3. Always refer to a "Rug" for pieces measuring 5'x8' or less, and a "Carpet" as 6'x9' and over. Like to get more technical? A rug measuring less than 3 feet in width and over 6 feet in length should be considered a runner. A carpet measuring 3 foot to 4 foot wide and over 7 feet long should be termed as a "wide runner." A carpet measuring 4 feet to 5 feet wide and over 10 feet long is considered a "Gallery Runner." A round rug is called a round, a square rug is called a square.
4. Never refer to a hand tufted, hand hooked or machine made rug as an "Oriental Rug." This is one of the most common mistakes. Although an machine made rug may have a Persian Design, it should never be considered an "Oriental" as this has certain implications in regards to both construction and manner of manufacturing.
5. Do not act as though knot count is everything! Again, this is one of the biggest mistakes novices make. Knot count means nothing if the quality of wool is shoddy. Knot count can also be easily misrepresented to the newbie, as many people don't understand the different construction and offset of looms. A carpet with symmetrical knots with no offset can easily be pawned off to the unsuspecting buyer as having a significantly higher knot count than previously thought. Similarly, there are rugs which come from certain areas which have a stylized knot such as some newer pieces which have come from China. Although knot count may appear to be high, the manner of constructing such knots may have been a deviation from how they should be tied. Shortcuts in weaving can give you a bad rug burn!