People have coveted natural Pearls as symbols of wealth and status for thousands of years with the oldest mention of natural pearls in 2206 BCE. The formation of Pearls may form in any mollusk. However, not all pearls are of the nacreous type commonly seen in jewelry. This includes uncultured rare Pearls such as – Clam, Melo, Conch etc.
Due to demand, people have found ways culture Akoya, South Sea, Tahitian and Freshwater Pearls, which now make up a bulk of the market. This makes the natural (uncultured) Pearls of any of these varieties rare and highly valuable.
General Pearl Grading
The qualities that determine the overall value of a natural or cultured pearl are:
- Size: Measures diameters of round Pearls in millimeters (mm)
- Shape: Round shaped is the most highly valued. Other shapes include mabe, drop, baroque etc.
- Colour: Primary body colour, core colours (if any), and the overtones (if any)
- Luster: refers to how sharp a reflection on the pearl is
- Surface Quality: refers to the dents and pits on the pearl surface
- Nacre Quality: refers to the nacre thickness of the pearl
- Matching: refers to the similarity in Pearls when paired or matched in jewellery
Some Pearls may be dyed, coated, bleached, filled or irradiated to either enhance their luster or alter the Pearl color. Dyed cultured pearls are usually detectable because they look artificial to the unaided eye. However, dyed Pearls of lighter tones can be difficult to detect.
Akoya Cultured Pearls are grown in Japan and China in saltwater mollusks. They come in white, cream or light grey, some with hints of pink or green. Brands like Mikimoto and Tasaki are famous for their use of Akoya Pearls. These Pearls are more expensive than freshwater pearls as each mollusk rarely produces more than two Pearls per harvest unlike freshwater oysters which can produce up to forty.
Also, Akoya Pearls are well known for their incredible luster and pink sheen on their white Pearls. The best Akoya Pearls are without the Shimi Effect (dark core) and have a nice pink overtone when light reflects off its surface. These qualities make Akoya Pearls look luxurious and a fine gem to use in any designer jewellery. Most Akoya Pearls are around 8mm to 10mm in diameter. Akoya Pearls above 10mm have an exponential increase in price and are considered rarer in the market.
*Shimi Effect is a term used by Japanese Pearl Dealers to describe Pearls that have a dark core. This happens when the oyster has an allergic reaction to the implanted shell bead nucleus, creating a dark scab over the nucleus before coating it with layers of nacre. As the nacre layers are translucent, this lightens the dark core, but it is still visible as a greyish tone in white Pearls, or greenish in golden Pearls.
Unknown to many, Akoya Pearls are also all treated in solution called the Maeshori Process which removed impurities in between the nacre layers. This process gives it that incredible metallic luster and shine that comes with inside the Akoya, rather than just the surface, and enhances the pink overtone. The Maeshori Process is also used on some South Sea Pearls to achieve a better luster.
South Sea Pearls
South Sea Pearls are cultured in Australia, Indonesia and the Philippines. They are found in saltwater and come in yellow, white and golden. Golden South Sea Pearls are only farmed in the Philippines in a specific species of oysters that do not grown in Indonesian or Australian environments.
The most common South Sea Pearls are size 8mm to 15mm. In our inventory, we carry many Pearls of these sizes in a variety of grades and colours. Sizes 15mm and above have an exponential increase in price and must be sourced individually.
Like all the other Pearls, the colour of the South Sea Pearl plays an important role in determining prices.
For White South Sea Pearls:
- Primary Colour: Is the main body colour white or cream?
- Dark Cores: Is the Shimi Effect present? Does the Pearl look dark or greyish under a light?
- Overtones: Do you see a pink glow on the surface of the Pearl?
The most expensive White South Sea Pearls are White + Without Shimi Effect + Pink Overtone keeping all the other variables such as size, luster, surface quality constant.
For Golden South Sea Pearls:
- Primary Colour: Is the main body golden or less saturated (closer to yellow)?
- Dark Core: Is the Shimi Effect present? Does the Pearl look dark or greenish under a light?
The most expensive Golden South Sea Pearls are Golden + Without Shimi Effect keeping all the other variables such as size, luster, surface quality constant.
As mentioned like the Akoya Pearls, South Sea Pearls may also go through the Maeshori Process to enhance its satiny luster from within. Sometimes larger South Sea Pearls may be polished to achieve a better surface luster. Golden South Sea Pearls which undergoes the Maeshori Process may end up with a lighter colour, hence sometimes these Pearls would undergo a slightly different process called the Bio-treatment instead. These are all trade secrets and the exact chemical formula is kept within each Pearl processing plant.
In our events, we have shared our experience at a South Sea Pearl Polishing Plant that polishes Pearls into the round shape and improve the surface luster using a few different techniques. Find out more here!
China and the United States are leading sources for freshwater cultured pearls. However, the global Freshwater Pearl market is overwhelmingly dominated by Chinese Pearl Farms which accounts for almost of the Pearls we see in the market today.
Freshwater pearls are usually cultured in lakes and ponds and have a wide range of colors. They are very often dyed, and mass produced.
Freshwater Pearls has a distinctive surface texture and the warmth of its luster. The nacre of a high-quality Freshwater Pearl does not usually have the glossy, metallic finish found in Akoya Pearls. In appearance, its finishing looks spotty and blurrier than Akoya Pearls or South Sea Pearls.
Tahitian cultured pearls are primarily cultivated around the islands of French Polynesia. They are grown in saltwater and come in eggplant purple, peacock green and various tones of grey.
In addition to the body color, Tahitian Pearls can display an amazing range of overtones, especially in baroque shapes. Traditionally the most sought after and expensive Tahitian Pearls will have a dark green body color and peacock overtones – green and a slight pink.
Non nacreous pearls – Conch, Clam, Melo
A conch pearl is a calcareous concretion produced by the Queen conch mollusc, which is a large, edible sea snail. Most often pink and pastel-hued in colour, it normally has an oval shaped. The finest quality Conch Pearls exhibit a wave-like “flame” structure on their surface and have a creamy, porcelain-like appearance and unique shimmer. It is one of the rarest and most expensive types of Pearls traded in the market, with prices going more than USD$10,000 per carat.
Melo Pearls are natural, non-nacreous calcareous concretions by the marine gastropod species known as Volutidae—a large sea snail dubbed Melo Melo. Melo Melo pearls are orange to tan to brown in color, with orange the most sought after colour. They are found in the South China Sea and west to the Andaman Sea off the coast of Burma. Like conch pearls, Melo Pearls do not contain nacre; instead their composition is calcite and aragonite, giving them a fine glazed surface that sometimes bears flamelike patterns like the Conch Pearl.
Tridacna squamosa or common clam is a giant clam producing glossy, translucent pearls with flame effects. Made of prisms of aragonite, its Pearls have a fine silk-like luster, often only seen in reflected light.
The best rule to remember is that Pearls are the last thing you put on and first thing you take off when getting dressed. For routine care, wipe pearls with a soft, clean cloth after each wearing. Pearls should never be cleaned in an ultrasonic cleaner. It’s safe to use warm, soapy water for occasional, thorough cleaning.