Pearl: meaning, properties and lore

The mineral

Pearl is organic because it comes from a living marine creature. Its composition is calcium carbonate in the form of aragonite, together with organic conchiolin. On the Mohs scale its hardness is 2.5–4.5, so it is a soft gem.¹⁴²

Pearl has a specific gravity of 2.60-2.85 and a refractive index of 1.52–1.69, which describe how heavy it is and how it bends light. It has an amorphous structure with no cleavage, and it is opaque with a pearly luster. Its luster comes from light reflecting off the surface and from concentric inner layers of nacre. Nacre quality matters, because a visible nucleus or a dull, chalky look indicates thin nacre.²¹⁵

Pearl occurs in white, black, gray, yellow, orange, pink, lavender, green and blue. Its colour has three components: bodycolor, overtone and orient, and all pearls show bodycolor while only some show overtone or orient. Pearl colours tend to be muted, with a soft, subtle quality. Commonly, pearls are dyed black or dark blue to give them a more valuable colour and increase their overtone.²³⁴⁵¹

Pearls fall into two varieties. Nacreous pearls resemble mother-of-pearl with lustrous nacre, while non-nacreous pearls, such as conch or melo pearls, lack lustrous nacre and often display flame structure on the surface. Natural pearls form around a microscopic irritant in the bodies of certain mollusks, while cultured pearls result from the deliberate insertion of a bead or piece of tissue that the mollusk coats with nacre.⁶²³⁴

Almost all pearls on the market are cultured, produced by inserting a nucleus into an oyster or mussel, and cultured pearls range from 2-16mm in diameter depending on the mollusk used. Natural and cultured pearls can be distinguished using x-ray equipment that examines the nucleus. Round is the most difficult pearl shape to culture, which makes it the rarest cultured shape.¹²⁵

Pearls form in ponds, lakes, seas and oceans. Most saltwater pearl culturing takes place in the Indian and South Pacific Oceans, and freshwater pearls are cultured primarily in China and Japan and in several states in the U.S. Tahitian cultured pearls come mainly from French Polynesia and are sometimes called black pearls. Pinctada maxima grows gold-lipped cultured pearls from Australia, Indonesia, the Philippines and Myanmar.⁷¹³

History and lore

Pearls have been highly valued as gemstones since antiquity, and their difficulty to obtain magnified their allure in early times. Pearls have been prized by many cultures throughout history and are frequently referred to as "The Queen of Gems". People have coveted natural pearls as symbols of wealth and status for thousands of years. The name pearl comes from an Old French word, perle.¹⁶⁷⁴

A Chinese historian recorded the oldest written mention of natural pearls in 2206 BC, and the Shu King, a 23rd-century B.C. Chinese book, describes a lesser king sending strings of pearls not quite round as tribute. In ancient China, pearls were believed to guarantee protection from fire and fire-breathing dragons. In Europe, pearls symbolized modesty, chastity and purity. Many cultures associated pearls with the moon because of the spherical shape of some pearls.⁷⁸⁴

Pliny, in his Natural History, wrote that the two pearls Cleopatra dissolved were worth an estimated 60 million sesterces. Historian Suetonius wrote that the Roman general Vitellius financed an entire military campaign by selling one of his mother's pearl earrings. Pearls were among the riches the Portuguese found in Quiloa's captured city, according to the report's account of the King of Quiloa's fall.⁸⁹¹⁰

Christopher Columbus repeatedly encountered native people adorned with natural pearls during his third (1498) and fourth (1502) voyages to the New World. Columbus's discovery of natural pearl sources in the waters of present-day Venezuela and Panama intensified demand in Europe. Within a hundred years, natural pearl sources had declined due to overfishing, pearl culturing, plastic buttons and oil drilling. Some outstanding sources of natural pearls before 1492 were the Persian Gulf, the waters of Ceylon, Chinese rivers and lakes, and the rivers of Europe.⁷

Kokichi Mikimoto successfully cultured a pearl in Japan in 1893, and Japanese pioneers produced whole cultured pearls around the beginning of the twentieth century. Cultured pearls became commercially important in the 1920s. From the 1930s through the 1980s, pearl culturing diversified and spread to various countries around the world. In 1917, Pierre Cartier traded a double strand of natural pearls for a mansion on Fifth Avenue in New York City.²⁸⁷

In Journey to the West, a lustrous pearl of mani is described as immune to spears and swords, and cannot be burned by fire or drowned in water. George Frederick Kunz, in his 1908 book The Book of the Pearl, stated his belief that an ancient fish-eating tribe, perhaps along the coast of India, first appreciated saltwater pearls found while opening oysters for food. Hindu legend has the god Krishna discovering pearls when he plucks the first one from the sea.¹¹⁸

The idea of a pearl classification system similar to GIA's 4Cs for diamonds first appeared in Gems & Gemology in 1942, in writings by Rietz. Rietz (1942) suggested grouping pearls by shape, luster, surface blemishes, color distribution and iridescence into categories from gem quality down to poor quality. In 1967 GIA's Richard T. Liddicoat Jr. proposed a new pearl classification system based on seven pearl value factors.⁶

Birthstone, zodiac and chakra links

Pearl is the June birthstone, and the Gemological Institute of America lists pearl as a United States birthstone for June, together with alexandrite and moonstone. Crystal practitioners also name pearl as the June birthstone, and they associate it with the third eye chakra, a link that is modern.⁷³

Crystal practitioners list pearl among the lucky birthstones for the Taurus modern modern modern zodiac sign (Apr. 21 to May 20), a modern link set by practitioners. Practitioners also link pearl to the numerical vibration 7, and they associate it with the Third Eye Chakra in a modern practice.

What crystal practitioners say

Crystal practitioners describe pearl as a gentle and nurturing stone associated with purity, wisdom and emotional balance. According to practitioners, it signifies faith, charity and innocence. Pearl is known as a "stone of sincerity", and practitioners associate it with bringing truth to situations and promoting loyalty.

Practitioners associate pearl with concentration, focus, meditation and tranquility. Crystal practitioners treat it as a stone for quiet reflection, and they associate it with calm rather than action.

Pearls are said to be softer gems that should be stored separately and wrapped in cloth to avoid scratches. Crystal practitioners who use pearl in their work, as the mineral claims show, advise against exposing it to sunlight and heat that fade it.

Crystal healing traditions say pearl helps relieve bloating and biliousness.

What testing has found

Edzard Ernst, in his analysis of 150 complementary and alternative treatments, concluded that no rigorous trials have tested the therapeutic value of crystal healing. He found no scientific proof that crystal healing has any positive effect beyond placebo.¹²

In a 2001 experiment, British psychologist Christopher French asked 80 volunteers to distinguish genuine crystals from imitations after holding them and meditating. Their reports were much the same for both kinds, which points toward a placebo effect.¹²

Jarry explains that alternative medicine's reputation benefits strongly from non-specific placebo effects and from people who publicly testify to improvement after using crystals. Ernst says that pleasant feelings or seeming successes of crystal healing can be attributed to the strong placebo effect or to believers seeing only what supports their belief, which is cognitive bias.¹²