a weight measure used by the Japanese for centuries. Today, momme weight is still the standard unit of measure used by most pearl dealers to communicate with pearl producers and wholesalers. One momme corresponds to 1/1000 kan. Reluctant to give up tradition, the Japanese government formalized the kan measure in 1891 as being exactly 3.75 kilograms or 8.28 pounds. Hence, 1 momme = 3.75 grams or 3750 milligrams. In the United States, during the 19th and 20th centuries, through trade with Japan in silk cloth the momme became a unit indicating the quality of silk cloth. Though millimeter size range is typically the first factor in determining a cultured pearl necklace's value, the momme weight of pearl necklace will allow the buyer to quickly determine if the necklace is properly proportioned. This is especially true when comparing the larger south sea and Tahitian pearl necklaces. In jewelry The value of the pearls in jewelry is determined by a combination of the luster, color, size, lack of surface flaw and symmetry that are appropriate for the type of pearl under consideration. Among those attributes, luster is the most important differentiator of pearl quality according to jewelers. All factors being equal, however, the larger the pearl the more valuable it is. Large, perfectly round pearls are rare and highly valued. Teardrop-shaped pearls are often used in pendants. Gallery Shapes Pearls are generally of spherical shapes. Perfectly round pearls are the rarest and most valuable shape. Semi-rounds are also used in necklaces or in pieces where the shape of the pearl can be disguised to look like it is a perfectly round pearl. Button pearls are like a slightly flattened round pearl and can also make a necklace, but are more often used in single pendants or earrings where the back half of the pearl is covered, making it look like a larger, rounder pearl. Pear-shaped pearls sometimes look like teardrop pearls and are most often seen in earrings, pendants, or as a center pearl in a necklace. Baroque pearls have a different appeal; they are often highly irregular with unique and interesting shapes. They are also commonly seen in necklaces. Circled pearls are characterized by concentric ridges, or rings, around the body of the pearl. In general, cultured pearls are less valuable than natural pearls, whereas imitation pearls have almost no value. One way that jewelers can determine whether a pearl is