You can grade pearls according to the following pearl grade factors: Size************************************************************************************************************************************* Size means the pearl's diameter measurement. Pearl size is expressed in millimeters, rounded to the nearest 0.5MM. Salt water cultured pearls range from 2MM to 11MM. Most common sizes are from 5MM to 8MM. A 10MM salt water cultured pearl is uncommon, and an 11MM is rare. Generally, if other pearl grade value factors are equal, the value of salt water cultured pearls rise gradually with their size. Shape*********************************************************************************************************************************** Pearls are graded by shape into four levels: Semi-baroque and baroque, Off round, Slightly off round, and Round. Semi-baroque and baroque are pear-shaped or irregular shape and are listed separately. Off-round pearls have flattening on one side or are ovalish. AAA+ and AAA grade pearls are all round and mostly round of pearls. AA+ and AA grade pearls are mostly round to slightly off round. A+ and A grade pearls are mostly round to slightly off round. Color*********************************************************************************************************************************** Pearl color is a combination of body color and overtone. Body color is the predominant basic color of the pearl. When pearls lay on a white surface, body color can be best seen on the outer edge of the pearl. Body colors include white, light pink or pink, light cream, and dark cream, yellow or golden. Overtone is one or two colors that overlie the body color. When inspecting pearls under light, you may see color in the central dark areas of the pearls. This is the overtone. Overtone colors include pink, silver, and green. You should remember that pearl color for the purposes of grading is not a measure of the beauty of pearls or your choice of pearl color. Pearl color relates to an aspect of pearl quality measured by pearl color. It is important to remember that what color of pearls is the most desirable in one market or culture may not be desirable in another. With salt water cultured pearls, the color and intensity of the color is a distinguishing feature of pearl quality. Low quality pearls often have brown or yellowish body color and do not have overtone or very light overtone. Pearls without overtone look "flat". High quality pearls have deeper overtone color, because the intensity of color is the result of thick nacre and high luster. Pearl processing also effect pearl color. Generally, salt water cultured pearls have four basic body colors: white, cream, pink and yellow and two overtones: rose (pinkish) and green. AAA+ and AAA grade pearls are white or pink body color with rose or gray overtone. AA+ and AA grade pearls are white, light creamy with rose or gray or light green overtone. A+ and A grade pearls are white, medium creamy, pink body color with rose, gray or green overtone.

Luster********************************************************************************************************************************** Luster is the surface brilliancy of pearls. It is probably the best expression of a pearl's beauty. Luster does not simply mean a shiny surface It implies the structural beauty of the nacre. We grade pearl luster in six levels: Very Low, Low, Good, High, Very High and excellent. Pearls with a very high luster will generally show strong and sharp light (mirror like) reflection of the light source. AAA+ and AAA grade pearls have excellent to very high luster. AA+ and AA have high to good luster. A+ and A grade pearls have good to medium luster. Pearls with a very low luster look very milky or chalky. They show very little highlights. SurfaceQuality*************************************************************************************************************************** All the factors that disturb the surface smoothness of the pearl and hence decide its appearance are called blemishes and imperfections (also called spots or flaws). The quality of the pearl is greatly affected by blemishes. Natural blemishes are formed during pearl cultivation. By definition, a blemish is anything that can be seen by unaided eyes. When grading an individual pearl (for a pearl ring, for example), the degree of blemish is divided into clean, slight spot, medium spot and heavy spot according to number, size, kind and location of the blemish. We reject pearls that exhibit excessive amounts of blemishes, such as cracks throughout the pearls, prominent flaws in a single pearl, patches of missing nacre, obvious discoloration's throughout the pearls, and flaws which cover the majority of the surface of the pearls. When grading a whole strand of pearls (for a necklace, for example), we determine what percentage of pearls have blemishes. The less such pearls the better quality of the strand. We grade surface quality of a pearl strand by determining what percentage of pearls have blemishes. AAA+ and AAA grade Akoya pearls are unblemished to very slightly blemished pearls. AA+ and AA grade pearls are very lightly blemished to slightly blemished pearls. A+ and A grade pearls are slightly blemished to lightly blemished. For a strand of pearls, 0-5% pearls with blemishes is considered unblemished to very slightly blemished. 10-20% is very slightly blemished, 20-30% is slightly blemished to lightly blemished. Pearl strands that have more than 40% of the pearls with blemishes are rejected. NacreThickness********************************************************************************************************************* Nacre is the coating that the oyster forms around the nucleus of the pearl. Nacre thickness is more than the amount of nacre. It has other meaningful aspects as well. The structure of the nacre is composed of thousands of layers of thin calcium carbonate crystals. This distinctive nacre structure influences the color, luster, durability and elasticity of the pearl. AAA+ and AAA grade Akoya pearls have very thick nacre (0.5mm and up) AA+ and AA grade pearls have thick nacre (0.25 to 0.4MM), A+ and A grade pearls have medium nacre (0.2 to 0.3MM). Pearls with very thin nacre allow the core nuclei to be seen through the nacre. Pearls with very thin nacre often exhibit visible cracks in the nacre. Pearls with very thin nacre can also display signs of nacre peeling or chipping. Matching*************************************************************************************************************************** Matching refers to all previously discussed factors: size, color, shape, luster, nacre and surface quality. Matching applies to pair of pearls and strand of pearls. AAA+ and AAA grade pearls are excellent to very good matching. AA+ and AA grade pearls are very good to good matching. A+ and A grade pearls are good matching.

How to put all the pearl grade factors together: A Pearls grade and value depends on how it combines the complete mix of these seven value factors. Since two strands of pearls in exactly same size maybe very different in other factors such as different color, different surface quality, so pearls are graded based on all other six factors. Additionally, not each of the factor weights the same. According to Gemworld International's Pearl Guide, the following percentages apply to the six factors except size: Color = 10% Shape = 15% Luster 25% Nacre = 25% Surface quality = 20% Matching = 5%. Total 100%