Pearl is produced through natural process. Natural pearl is made by oyster, but cultivated pearl is formed by mollusc. Different type of mollusc produces different shape, size and color of pearl. This helps in determining the price of each pearl.
Here are various factors that help in determining the quality –
- Surface Quality
- Nacre Quality
When an irritant like sand grain or fish bone enters the oyster shell, the oyster protects itself by covering it with fluid called nacre. Layers of nacre help in formation of a pearl. However, it is difficult to predict what shape a pearl will take after the process is complete. This can be seen only after the pearl is taken out from shell.
Although round shaped pearls are highly in demand, but there are other shapes like oval, button, drop, baroque and semi baroque that also look unique in different accessories.
Pearl’s diameter is measured in millimetres and large pearl like South Sea pearl is considered valuable. There are tiny pearl gems available as well, but they will be less effective and can be affordable. With increase in every one millimetre in size, the price increases rapidly.
No matter what color of pearl you choose, its body color, overtone and surface that reflects rainbow color gives it a value. There are varieties of colors available, but not all color stones will have overtone.
Overtone is the translucent shade that appears on the surface when light reflects on it. Theses overtones add depth to the gem. For example white pearl can have pink overtone and black pearl can have peacock green overtone.
Lustre is the brightness on every pearl that is created by the layers of nacre. Lustre is formed by the deep glow that appears when light falls on the pearl. An excellent quality of pearl will let you see your reflection when light falls on it.
There may be blemishes on a pearl which makes it authentic. However, more blemishes will be hindrance to its lustre. Therefore, pearl with cleaner surface is considered valuable. Pearls with blemishes are less valuable.
Nacre is the main ingredient in the recipe that gives flavour to a pearl. It is a fluid which is excreted by mollusc to cover the irritant to make smooth. Nacre is numerous layers of overlapping thin crystal plates that have irregular edges. If nacre is thick the quality of pearl will be good, but if the layer is thin, then the pearl can have a dull and chalky appearance.
It is difficult to match identical pearls to make a necklace. This is why real pearl necklaces are expensive but makes her look graceful.