MINERAL: Calcium Carbonate
COLOR: White, black, gray, yellow, orange, pink, lavender, green, blue
REFRACTIVE INDEX: 1.52-1.69
SPECIFIC GRAVITY: 2.60-2.85
MOHS HARDNESS: 2.5-3.0
China, Japan, Philippines, Australia, French Polinesia.
Birthstones & Anniversaries
Pearl is the birthstone for June and the gem of the third and thirtieth anniversaries.
Perfect shining spheres. Lustrous baroque forms. Seductive strands, warm to the touch. Pearls are simply and purely organic.
Perhaps the best-loved gems of all time, pearls—natural and cultured— occur in a wide variety of colors. The most familiar are white and cream, but the palette of colors extends to every hue. Natural pearls form around a microscopic irritant in the bodies of certain mollusks. Cultured pearls are the result of the deliberate insertion of a bead or piece of tissue that the mollusk coats with nacre.
Perhaps the best-loved gems of all time, pearls—both natural and modern cultured pearls—occur in a wide variety of colors. The most familiar colors are white and cream (a light yellowish brown). Black, gray, and silver are also fairly common, but the palette of pearl colors extends to every hue. The main color, or bodycolor, is often modified by additional colors called overtones, which are typically pink (sometimes called rosé), green, purple, or blue. Some pearls also show the iridescent phenomenon known as orient.
Cultured pearls are popular for bead necklaces and bracelets, or mounted in solitaires, pairs, or clusters for use in earrings, rings, and pendants. Larger pearls with unusual shapes are popular with creative jewelry designers.
Pearl—natural or cultured—is a US birthstone for June, together with alexandrite and moonstone.
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.
There are four major types of cultured whole pearls:
– Akoya—This type is most familiar to many jewelry customers. Japan and China both produce saltwater akoya cultured pearls.
– South Sea—Australia, Indonesia, and the Philippines are leading sources of these saltwater cultured pearls.
– Tahitian—Cultivated primarily around the islands of French Polynesia (the most familiar of these is Tahiti), these saltwater cultured pearls usually range from white to black.
– Freshwater—These are usually cultured in freshwater lakes and ponds. They’re produced in a wide range of sizes, shapes, and colors. China and the US are the leading sources.
People have coveted natural pearls as symbols of wealth and status for thousands of years. A Chinese historian recorded the oldest written mention of natural pearls in 2206 BC. As the centuries progressed toward modern times, desire for natural pearls remained strong. Members of royal families as well as wealthy citizens in Asia, Europe, and elsewhere treasured natural pearls and passed them from generation to generation.
From those ancient times until the discovery of the New World in 1492, some of the outstanding sources of natural pearls were the Persian Gulf, the waters of Ceylon (now Sri Lanka), Chinese rivers and lakes, and the rivers of Europe.
During Christopher Columbus’s third (1498) and fourth (1502) voyages to the New World, he repeatedly encountered native people adorned with natural pearls. His discovery of natural pearl sources in the waters of present-day Venezuela and Panama intensified demand in Europe. However, within a hundred years, these natural pearl sources had declined due to overfishing, pearl culturing, plastic buttons, and oil drilling.
The first steps toward pearl culturing occurred hundreds of years ago in China, and Japanese pioneers successfully produced whole cultured pearls around the beginning of the twentieth century. These became commercially important in the 1920s (about the same time natural pearl production began to decline). From the 1930s through the 1980s, pearl culturing diversified and spread to various countries around the world.
Pearls are treasures from the Earth’s ponds, lakes, seas, and oceans, and they’ve always embodied the mystery, power, and life-sustaining nature of water.
The spherical shape of some pearls led many cultures to associate this gem with the moon. In ancient China, pearls were believed to guarantee protection from fire and fire-breathing dragons. In Europe, they symbolized modesty, chastity, and purity.
PEARL QUALITY FACTORS
The qualities that determine the overall value of a natural or cultured pearl or a piece of pearl jewelry are size, shape, color, luster, surface quality, nacre quality, and—for jewelry with two or more pearls— matching.
When other value factors are equal, larger pearls are rarer and more valuable than smaller pearls of the same type.
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.
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.
Like colored 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.
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 colors tend to be muted, with a soft, subtle quality.
Pearl color can have three components. Bodycolor is the pearl’s dominant overall color. Overtone is one or more translucent colors that lie over a pearl’s bodycolor. And orient is a shimmer of iridescent rainbow colors on or just below a pearl’s surface. All pearls display bodycolor, but only some show overtone, orient, or both.
The law of supply and demand determines the value of certain pearl colors at any given time. If supplies of high-quality pearls displaying a preferred color are low, their prices can rise to unusually high levels. Other complex factors, like fashion trends and cultural traditions, can influence color preferences.
Jewelry designers sometimes deliberately mix colors, shapes, and sizes for unique effects, but for most pearl strands, earrings, or other multiple- pearl jewelry, the pearls should match in all the quality factors.