"Rugs as an Investment": A comprehensive guide to 19th- and 20th-century oriental rugs, by Parviz Nemati, Agate Press, Charles E. Tuttle Co.

Nemati, a New York collector and dealer in oriental rugs, remembers a reception his father gave for foreign diplomats. He spread rugs from the family workshop, over the courtyard, to the street. A photograph of the time shows them sitting on bentwood chairs and folding seats amidst rugs hanging on the ceiling, covering the floors, a tent of pattern.

Oriental carpets have been collected in Europe for 800 years or so, but Nemati dates collecting in American to the 1876 Centennial. William Sloane, founder of W. J. Sloane, the furniture store which still has a Washington branch, bought the whole exhibit, and other stores followed.

Nemati cites the figures of a Viennese dealer to show the gains in rug prices. "Using the year 1976 for the base figure of 100 . . . by 1979 Heriz rose to 198, Sarouk to 224, Shiraz and Ghasghai registered even stronger gains at 250 and 256 respectively, Bokharas rose to 193, Kazak to 269, and Shirvan was the strongest at 295." He thinks that oriental rugs are still underpriced as compared to other art forms. And he thinks that the United States may be one of the best places to buy rugs.

Nemati traces the origins, designs, and techniques of old and new rugs from different sections: Turkish, Persian, Caucasian, Turkoman, Indian, Chinese, European. The book also lists major collections, dealers and a glossary. Most important of all, the book contains 102 well-printed color plates of rugs magnificently photographed by Thomas Feist and Ernest Silva.

"Oriental Rugs," by Walter Denny, the Smithsonian Illustrated Library of Antiques, Cooper Hewitt Museum.

A rug, points out Denny, is a heavy textile meant to be used in the form in which it left the loom, uncut and rarely sewn. A carpet is a big, flat rug.

Rugs, he writes, are the warp and woof of life in some societies -- hammocks for babies, carpet bags for worldly possessions, dowries for women, artistic medium, coin of trade.

The rug belt is the temperate zone, warm enough to raise animals for fibers and plants for dyes, cool enough to need rugs. Rugs are made from Spain to China, from Mongolia to Africa, Egypt, Syria, Asia Minor, the Balkans, Iran and India -- places where sheep are grown, handicrafts encouraged and labor cheap.

Wool even today is considered the best of rug fiber because of its resistance to wear, rot and mildew.Cotton has been popular for its acceptance of color and its reflection of light. Cotton is easier to use and lies flatter. Silk, though it doesn't wear well and fades easily, is the most luxurious and fragile. All three are sometimes woven together.

The nomadic loom, Denny writes, a large wood rectangle, is used either flat or vertically. Warp is the longitudinal thread, the base. Weft is the latitudinal strand woven over and under the warp threads with two sticks, the shed stick and the heddle.

Pile rugs, the most familiar kind, are "made of row after row of tiny knots, tied on the warps of the foundation, which by the thousands combine to create a thick, fuzzy, light reactive fabric. To make a knotted-pile rug, the weaver starts at one side of the rug and ties a knot on the first two warps. Moving across the rug, the weaver continues along, using various colored yarns as required by the pattern and tying knot after knot on successive pairs of warps. Once a row of knots has been completed, the shed stick and heddle are manipulated and weft is shot across the rug, from one to as many as eight times.The weft is then beaten with a comb hammer to make the fabric solid and compact . . ." After a large area is knotted, the pile is trimmed to the proper length.

For years, Denny writes, the oldest carpets were thought to be 13th- or 14th-century, but in the late '40s, 5th-century felt and knotted-pile rugs were found in the frozen tombs of the Pazyryk Valley of the Altai Mountains of Siberia. The great 16th-century rug trade between Europe and the East is attested to in paintings of the period. This classic age of weaving imposed its designs on rugs to this day.

This informative book has 28 color plates, 79 black-and-white photographs and five maps.

If these books are not available at your local bookstore, your bookdealer can order them for you.