Pearl Quality Factors
The qualities that determine the overall value of a natural or cultured pearl or a piece of pearl jewellery are size, shape, colour, luster, surface quality, nacre quality, and—for jewellery with two or more pearls—matching.
Size: When other value factors are equal, larger pearls are rarer and more valuable than smaller pearls of the same type.
Shape: Round is the most difficult shape to culture, making it the rarest cultured pearl shape and—if all other factors are equal—also generally the most valuable. There are exceptions, though. Well-formed pear, oval, or baroque (irregularly shaped) cultured pearls are also prized by pearl lovers.
Colour: Natural and cultured pearls occur in a broad range of hues. There are warm hues like yellow, orange, and pink, and cool hues like blue, green, and violet. Pearls have a wide range of tone from light to dark. Pearl colours tend to be muted, with a soft, subtle quality.
Pearl colour can have three components. Bodycolour is the pearl’s dominant overall colour. Overtone is one or more translucent colours that lie over a pearl’s bodycolour. And orient is a shimmer of iridescent rainbow colours on or just below a pearl’s surface. All pearls display bodycolour, but only some show overtone, orient, or both.
The law of supply and demand determines the value of certain pearl colours at any given time. If supplies of high-quality pearls displaying a preferred colour are low, their prices can rise to unusually high levels. Other complex factors, like fashion trends and cultural traditions, can influence colour preferences.
Luster: Of the seven pearl value factors, luster might be the most important. Luster is what gives a natural or cultured pearl its unique beauty.
- Excellent – Reflections appear bright and sharp
- Very Good – Reflections appear bright and near sharp
- Good – Reflections are bright but not sharp, and slightly hazy around the edges
- Fair – Reflections are weak and blurred
- Poor – Reflections are dim and diffused
Within a pearl type, when other value factors are equal, the higher the luster, the more valuable the pearl.
Surface quality: Like coloured stones, most pearls never achieve perfection. Some might show abrasions that look like a series of scratches on the surface, or a flattened section that doesn’t affect its basic shape, or an irregular ridge that looks like a crease or wrinkle.
If surface characteristics are numerous or severe, they can affect the durability of the pearl and severely depress its value. Surface characteristics have less effect on the pearl’s beauty and value if they are few in number, or if they are minor enough to be hidden by a drill-hole or mounting.
Nacre quality: Luster and nacre quality are closely related. If the nucleus is visible under the nacre, or if the pearl has a dull, chalky appearance, you can assume that the nacre is thin. This affects the luster as well as the durability of the pearl.
Natural Pearls Vs. Cultured Pearls
Natural pearls form in the bodies, or mantle tissue, of certain mollusks, usually around a microscopic irritant, and always without human help of any kind.
The growth of cultured pearls requires human intervention and care. Today, most of the mollusks used in the culturing process are raised specifically for that purpose, although some wild mollusks are still collected and used.
To begin the process, a skilled technician takes mantle tissue from a sacrificed mollusk of the same species and inserts a shell bead along with a small piece of mantle tissue into a host mollusk’s gonad, or several pieces of mantle tissue without beads into a host mollusk’s mantle. If a bead is used, the mantle tissue grows and forms a sac around it and secretes nacre inward and onto the bead to eventually form a cultured pearl. If no bead is used, nacre forms around the individual implanted mantle tissue pieces. Workers tend the mollusks until the cultured pearls are harvested.
Pearl Types
There are five major types of cultured whole pearls:
Keshi Pearls:
Keshi pearls are small non-nucleated pearls typically formed as by-products of pearl cultivation. A Japanese word also meaning "poppy", it is used in Japanese for all pearls that grew without a nucleus. Originally, keshi pearls referred to those pearls formed when a bead nucleus was rejected.
Akoya (Pinctada Imbricata) Cultured Pearls:
Akoya cultured pearls are the most familiar type of saltwater cultured pearl to most people in the U.S and other western markets. Many customers think of white or cream coloured akoyas as the classic pearl used for jewelry, especially single-strand necklaces. Japan and China both produce akoya cultured pearls. This is the species I studied for my PhD :-)
South Sea (Pinctada Maxima) Cultured Pearls:
Australia, Indonesia, and the Philippines are leading sources of these saltwater cultured pearls. South Sea cultured pearls can be white to silver or golden, depending on the type of oyster. Their large size and thick nacre, due to a long growth period, plus their limited critical growing conditions are all factors contributing to their value.
Tahitian (Pinctada margaritifera) Cultured Pearls:
Cultivated primarily around the islands of French Polynesia (the most familiar of these is Tahiti). These saltwater cultured pearls, sometimes referred to as black pearls, have a wide color range. They might be gray, black or brown, and they can have blue, green, purple or pink overtones.
Freshwater (Hyriopsis cumingi (triangle shell) and Hyriopsis schlegeli (Biwa shell) Cultured Pearls:
Freshwater cultured pearls are the most commonly produced pearls and they are one of the most popular pearl types among shoppers and jewelry designers. This is due to their remarkable range of sizes, shapes and colors, plus their commercial availability at lower price points. They are usually cultured in freshwater lakes and ponds, often with many pearls grown in one oyster. China is the leading source for freshwater cultured pearls.
