Pearls from different parts of the world are classified by different shapes. These are not considered baroque meaning misshapen pearls rather they are considered fancy shapes, very much like fancy shape diamonds (diamonds other than the round brilliant). Symmetrical pearls would include oval, button and drop. The best pearls are round, and when all pearls on a necklace form perfect circles, the cost increases significantly. Generally pearls are placed into 3 categories for shape: round, symmetrical and baroque. Pearls are cultured in many shapes, by simply inserting nuclei with different shapes. It happens gradually, and the process is hastened by the use of perfume and hair spray. Within a few years, many of the pearls become lifeless. It is merely reflected light from surface polish, and it does not last. This is NOT refracted light from thick nacre. Modern polishing techniques have improved surface reflection of light, so when the necklace is new, the pearls still look pretty. Sadly, most pearls are removed and brought to market more quickly. Expert pearl buyers can determine the growth period (and therefore estimate nacre thickness) just by eyeing the luster, and can also easily distinguish the difference between the glow from heavy nacre and the glow from reflected light from surface polish. Nacre thickness is impossible to measure but can be determined by X-ray. 8mm of nacre, which is still more than sufficient to produce wonderful pearls. Modern techniques allow farmers to reduce the growth period to 2 years, and the finest quality necklaces today exhibit about. Before World War II, it was not uncommon for pearls to be left growing from 4 to 6 years, producing almost 1mm of nacre around the nucleus, resulting in gorgeous luster. Luster is defined as the quantity and quality of light that refracts from the layers of nacre and combines with the reflection of light from the surface of the polished pearl. More layers of nacre produce brighter and richer luster and therefore more beautiful pearls. Thicker nacre will be produced if the nucleus is left longer inside the mollusk. The thickness of nacre surrounding the center nucleus is the most important determinant of cost of a cultured pearl necklace. NACRE THICKNESS FROM LONGER GROWING PERIODS Thickness of Nacre and Resulting Luster.Quality features apply to a single pearl, pearls on a necklace as well as pearls in all kinds of jewelry. Judging pearl quality is complicated and requires years of patient and continuous practice. This is called “matching.” Finally are the pearls properly and evenly drilled, and is the necklace strung with professionally tied knots. Judging a necklace or bracelet, each of these qualities is examined and rated by how well they match going up and down the entire length of the piece. Pearls are judged based on multiple features.These include the thickness of the layers of nacre, shape, body color, overtone color, polish and surface blemishes.
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