Pearl Knowledge

Pearl Grading Standard

The following factors are most recognized for determining a pearl’s value:



There are four main types of cultured pearls in the market today, each exquisitely unique in character. They are South Sea Pearl, Akoya Pearl, Tahitian Pearl and Freshwater Pearl.



Size of pearl greatly depends on the size of the pearl oyster, hence the type of pearl. Freshwater pearls range in size from about 3.0-7.0mm, Akoya pearls range from about 6.0-8.0mm, while South Sea and Tahitian pearls would range from about 11.0-14.0mm. Price increases with the size. If a pearl size exceeds the normal range of its specific type, its value could go up exponentially.



Main color of a pearl is called the body colour. Typical colors include white, yellow, pink, silver or black. A pearl can also have a hint of secondary color, named overtone. It is seen when light reflects off the pearl surface. For example, a pearl may appear white in general, but a pink overtone may become apparent when examined more closely.



Luster is what gives a pearl its unique beauty. The thicker the nacre layer, the better the pearl’s ability to reflect light. Richness of luster is also attributed to smoothness of pearl surface, evenness of nacre layer, and content of impurities. Higher luster, greater pearl value.



The closer to a true sphere, the higher the value of pearl. Shapes that are not spherical nor symmetrical are considered inferior. However, non-spherical pearls are sometimes used in special jewelry designs that appeal to many people.


Surface Quality

Flaws naturally arise during pearl’s formation, spots and bubbles easily appear in the layering process. Therefore, most pearls never achieve perfection. Highest-quality pearls are those with the smoothest surfaces and fewer number of flaws. Serious flaws might have impact on a pearl’s value and even hardness.


Akoya Pearl

Akoya pearls, also known as Japanese pearls, have been loved for centuries and are recognized around the world. Japan is a major producer of the Akoya pearl oyster which lives in calm inner bay waters with an optimal water temperature. Their shape is generally round and they come in an ordinary size of 6.0-8.0mm. An Akoya pearl larger than 8.0mm is considered rare and jumps significantly in price.


Akoya pearls are known for their stunning and elegant luster created by the delicate colors of the multilayered nacre. Colors include white, pink, silver, gold and cream, etc. Their white colour with pink overtone complement a fair complexion. The beautiful luster they boast makes them widely used in high-end jewelry.

South Sea Pearl

South Sea pearls are mostly cultured in the northern waters of Australia, South-east Asia, Indonesia and the Philippines. They possess extraordinary lustre and quality. Their size, smoothness and roundness are exceptional.


South Sea pearls have a broad range of colour. The silver-lipped oysters produce pearls with overtones of silvery white or bluish white, while the gold-lipped oysters produce pearls with overtones of gold, cream or silver. They are also the largest type of pearls with an average size of 11.0-14.0mm in diameter, and even up to 20.0mm in uncommon cases. Their rarity and sensitivity make them much more difficult to be cultivated, thus more valuable.

Tahitian Black Pearl

Tahitian pearls are renowned for their unique dark hue, large size and dramatic touch. They are exclusively cultured in the French Polynesian lagoons, the Cook Islands and Tahiti in particular. This oyster is very sensitive to the pearl culturing process, which makes the pearls very costly to produce.


Despite the fact that they are frequently called as black pearls, Tahitian pearls, harvested from black-lipped oysters, come in wide shades of metallic grey, silver, green, purple, blue to graphite. Specifically, peacock green Tahitian pearls in a stunning greenish-black hue resembling a peacock’s tail, are highly sought-after for the mysterious luster and rare nature. Ranging in size from 8.0-16.0mm in diameter, Tahitian pearl is a bit smaller than the South Sea pearl, but larger than the Akoya and Freshwater pearls.

Freshwater Pearl

Unlike sea water pearls which come from oysters living in salty sea water, freshwater pearls are cultivated from “”Triangle”” mussels that live in the freshwater lakes, ponds and rivers of China.


Freshwater pearls come in various colors, such as white, pink, orange, and other pastels, which can be achieved through natural culturing methods. It is also a widely-accepted practice to treat or irradiate Freshwater pearls in order to achieve a particular or unusual color, or to create a more evenly-coloured strand.


The Freshwater pearls look similar to Akoya pearls. But Freshwater pearls are generally smaller, less symmetrical, and not as lustrous. They are found in a wide range of shapes including round, oval, drop, button, baroque and stick. Using a special harvesting process, a number of pearls can be harvested from a single mussel. Hight yield of Freshwater pearls makes them priced much lower than Akoya pearls.

Pearl Care

1. Pearls are organic gemstones. Heat or UV rays may cause changes in color or deterioration in quality, therefore, do not expose pearls to direct sunlight or high heat or humidity.


2. When wearing pearl jewelry, avoid the pearls from coming in contact with sharp objects or other gemstones to avoid scratches or further damage to their tender surface.


3. Be sure to store pearls safely in an individual, soft-lined pouch, box or protective container and keep them separate from other items in the same jewelry box.


4. Pearls are vulnerable to acids and other chemicals. It’s important to keep them away from household chemicals including perfume, makeup and hairspray, etc.


5. Acids in perspiration would dull the pearls lustre. Wipe the pearl jewelry gently with a soft cloth after every wearing.


6. The best way to keep a pearl’s beauty is to wear often as the body’s natural oil keeps its lustre. When cared for properly, pearls can last a lifetime.