BMJ Blog

How Are Pearls Formed?

Posted on January 10, 2019 by Mary Hood | 0 Comments

Contrary to popular lore, pearls aren’t necessarily formed when a grain of sand enters an oyster. That’s likely a myth. Rather, pearls form when a tiny organism (probably a parasite) enters a shell-producing mollusk (a group that includes oysters, mussels, clams, marine snails, and abalone).

As a defensive mechanism, the mollusk forms a protective crystalline substance around the irritant. This protective substance is called “nacre.” Nacre is composed of calcium carbonate and protein, and it is both lighter and stronger than concrete. (It’s also the same substance that forms the inside of the mollusk’s shell.) Nacre gives pearls their gem-like luster.

How Are Pearls Formed?

Barbara Michelle Jacobs Green with Envy Pearl Ring

Natural pearls of real value occur very rarely, however. In fact, a pearl of value occurs in less than one of every 10,000 pearl oysters. Moreover, it can take at least three years for an oyster to coat an irritant with enough nacre to form a gem-quality pearl. Low-quality pearls are often the result of a pearl being “rushed out” of the oyster after less than a year. With these pearls, the coating of nacre is too thin to create adequate luster.

 

What Are the Different Kinds of Pearls? | Barbara Michelle Jacobs Jewelry

Barbara Michelle Jacobs Morganite Gemstone and Pearl Ring

Cultured pearls help meet the high demand for real pearls. In the case of cultured pearls, a bead or piece of shell called mother of pearl is surgically inserted into the oyster. The inserted piece is also sometimes called the “nuclei.” The mollusk reacts to the nuclei the same way it would to a natural parasite by layering it with nacre, thereby forming a pearl.

Although saltwater pearls have historically been considered more valuable, thanks to their natural roundness and luster, freshwater pearls, which were once usually irregularly shaped, may now look more like their saltwater counterparts due to advances in pearl farming technology. See more about the different types of real pearls.

What Are the Different Kinds of Pearls? | Barbara Michelle Jacobs Jewelry

Barbara Michelle Jacobs Vine and Pearl Gold Ring

Finally, there are imitation pearls, which are usually made by dipping a glass bead in a solution made of fish scales. Because nacre has a distinct grit, it’s usually possible to tell the difference between a real and imitation pearl by running your teeth over them. An imitation pearl will feel smooth while a real pearl, natural or cultured, will feel gritty.

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You may also be interested in: The Meaning of Pearls
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Photos: Barbara Michelle Jacobs Jewelry

Posted in gem facts, pearl jewelry, pearls

The History of The Enchanting Moonstone

Posted on June 07, 2018 by Mary Hood | 0 Comments

Gem Lore: Moonstone

Moonstone Pendant

The ever-captivating moonstone has been the subject of lore and fantasy across time and cultures—and it’s no wonder. The natural structure of moonstone beautifully scatters light, recalling the soft and luminous elegance of the moon itself (an effect known as adularescence that looks like a full moon shining through a thin veil of clouds—or moonlight glowing in water). In fact, according to Hindu mythology, moonstones are made of solidified moon beams. Furthermore, the Romans and Greeks associated moonstone with their lunar deities.

Moonstone used to be called “adularia,” a name that originated with a city in Switzerland, Mt. Adular (now St. Gotthard), one of the first sources of fine moonstone.

Like the moon, moonstone is often associated with feminine energy, sensitivity, and intuition. Moonstone has been so deeply associated with femininity that some beliefs connect it to pregnancy and childbirth.

Legends also say that moonstone helps you see the future (especially if the stone is placed in your mouth during a full moon). Other beliefs hold moonstone as a travel talisman, especially for those traveling at sea, a place ruled by the moon itself.

Moonstone Necklace Featuring Assorted Gems

Moonstone Necklace Featuring Assorted Gems

In the tradition of crystal healing, moonstone is believed to aid the pituitary gland and  the digestive system while reducing water retention and obesity. It’s also used to calm responses to stress and help its users avoid over-reacting to stressful moments.

Teardrop Moonstone Necklace

Teardrop Moonstone Necklace

Moonstone has also been featured in art throughout the ages. Artisans of the late nineteenth-century Arts and Crafts movement featured moonstone in handcrafted silver items, and later, René Lalique and Louis Comfort Tiffany of the Art Nouveau era used moonstone in their jewelry. Moonstone found contemporary appeal with the “flower children” of the 1960s who sought an ethereal look. New Age artists of the 1990s also turned to moonstone inspiration.

Rene Lalique Moonstone

Pocket watch by Rene Lalique (1860-1945), Ca. 1899-1900. Gold, enamel, moonstone.

 You may also be interested in: What is a Druzy? 

What Are the Different Types of Opals?

The Meaning of Pearls

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Photo: Max Pixels, Amelia Isa via Flickr, Siam Gem Palace

Posted in gem facts, gem lore, moonstone

May Birthstone: Emerald

Posted on May 04, 2018 by Mary Hood | 0 Comments

May Birthstone: Emerald

A stone with one of the richest histories in all of gem lore, the emerald continues to captivate and enchant jewelry lovers with its incomparable green hue. Because deep green emeralds with high clarity are quite rare (and incredibly valuable), the stone is often heat treated to enhance its natural color and improve its clarity. Emeralds are a variety of beryl—a mineral that grows with six sides and may grow up to a foot tall.

Gemologists consider emerald to be one of the oldest mined stones with evidence indicating that it was mined in Egypt as early as 330 B.C.E.—yet some estimates suggest that the oldest emerald stones may be up to 2.97 billion years old!

The name “emerald” comes from the Greek “smaragdus,” meaning green. Emeralds have been found in Columbia, Brazil, AfghanColombiaambia, and Egypt. The Egyptians featured emerald in their jewelry and burial rituals. Believed to be a symbol of protection, emeralds were often buried with monarchs. The stone was so greatly valued by Egyptians that Cleopatra claimed ownership of all emerald mines during her reign.

Roman scholar Pliny the Elder is credited with the following statement about the beautiful green stone:  "Indeed, no stone has a color that is more delightful to the eye, for, whereas the sight fixes itself with avidity upon the green grass and the foliage of the trees, we have all the more pleasure in looking upon the emerald, there being no gem in existence more intense than this.” Meanwhile, it’s believed that Roman emperor Nero would watch the gladiator games through thin, flat emeralds.

The Muzo tribe of Columbia had such well-hidden emerald mines that it took the Spanish conquistadors nearly twenty years to discover them. Indeed, the violent conflicts between natives of present-day South America and European colonists shadow the history of emerald acquisition (usually on behalf of royalty) in Western European countries.

Gold, set with table-cut emeralds, and hung with an emerald drop from Colombia, currently exhibited at Victoria and Albert Museum

Gold, set with table-cut emeralds, and hung with an emerald drop from Colombia, currently exhibited at Victoria and Albert Museum.

In addition to being seen as a protective force, over the centuries, emeralds have also been credited with the ability to cure stomach problems, control epilepsy, stop bleeding, and ward off panic and anxiety. Some cultures even believed that emeralds granted the owner foresight—when the emerald was placed under the tongue!

Emerald is still celebrated as a symbol of rebirth, new beginnings, loyalty, and security—making it a perfect birthstone for the lush month of May. This lovely stone also serves as a gift for 20th and 35th wedding anniversaries.

A beveled square-cut emerald in a platinum setting, surrounded by 109 round and 20 baguette cut diamonds.

Hooker Emerald Brooch, 1950. A beveled square-cut emerald in a platinum setting, surrounded by 109 round and 20 baguette-cut diamonds.

Are you a fan of emeralds?

See also: 

December Birthstone: Zircon

November Birthstones: Topaz and Citrine

The Meaning of Pearls

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Photos: Wikimedia Commons

Posted in beryl, birthstones, emerald, gem facts, gem lore

What Are the Different Types of Opals?

Posted on October 20, 2016 by Mary Hood | 0 Comments

Opals consist of hydrated silica and occur in rock fissures. Due to their structure, opals are considered mineraloids rather than minerals. Opals are the national gemstone of Australia but are also found in Ethiopia and Virgin Valley, Nevada.

Opal Lore

Opals have been the subject of various lore. During the Middle Ages, opals were associated with great luck and believed to carry the properties of every gem whose color matched one of the many colors reflected in the opal. Opals were also believed to bestow the power of invisibility. By wrapping an opal in a bay leaf and holding it in your hand, you could avoid being seen—or so the story goes.

Love of opals and belief in their inherent goodness dramatically changed with the publication of Sir Walter Scott’s Anne of Geierstein in 1829. The book describes a character who dies shortly after her opal comes into contact with a drop of holy water and turns black. Shortly after the book's publication, opal sales dropped by 50% in Europe and remained low for the next 20 years.

The Different Types of Opals

Natural

What Are the Different Types of Opals? | Barbara Michelle Jacobs Blog

Black Opal

Black/Dark Opals are the rarest and most valuable opals. Found in the Lighting Ridge in New South Wales, black or dark opals have a naturally dark background, which allows their colors and rainbow tones to appear more vibrant. This natural layer of potch (colorless opal) on the back of the stone varies in darkness; the darker the potch, the more vibrant the colors in the stone. The more vibrant the stone, the greater its value. Most black/dark opals are cut into ovals or teardrops.

What Are the Different Types of Opals? | Barbara Michelle Jacobs Blog

White Opal

White Opals or “milk opals” are light with a white body tone (as opposed to the black/dark body tone of the black/dark opals). Mined in southern Australia in the opal fields of Coober, Pedy, Mintabie, and Andamooka, white opals are the most common opals and therefore the least valuable--but they can still be quite pretty.

Crystal Opals can be light or dark and are partially transparent. Partial transparency may enhance the color (and value) of a stone. An opal with transparency may be referred to as a “white crystal opal” or “black crystal opal” depending on its body tone.

What Are the Different Types of Opals? | Barbara Michelle Jacobs Blog

Boulder Opal

Boulder Opals form in ironstone cavities in Queensland. They’re typically cut with some solid brown ironstone remaining on the back; the ironstone backing functions like the dark potch on black/dark opals, allowing the colors in the opal to stand out vibrantly. Found in Quilpie and Winton, boulder opals vary greatly in size and may be found as small as a pea or as large as a car. These are the second most valuable opals and are distinct for their thin, colorful veins. Boulder opals tend to have a flat or undulating surface and are almost always cut in a freedom shape, which maximizes the size the of the stone.

Matrix Opals occur as a network of veins between crevices in the host rock (usually claystone or ironstone). An andamooka matrix opal is a kind of matrix opal that has been enhanced by soaking in a sugar solution and boiled in acid, a process that deposits carbon in the stone’s pores, creating a darker background. A natural oulder opal matrix is a matrix opal in its natural state; it consists of brown ironstone with small deposits of opal.

What Are the Different Types of Opals? | Barbara Michelle Jacobs Blog

Polished Yowan Nut Opal

Yowan Nuts are found in Yowan in Queensland. These ironstone concretions resemble nuts, which can be cracked open to reveal a valuable opal in the center.

Synthetic/Manmade

Synthetic Opals are made in a lab with opaline silica, whose structure is similar to that of natural opal. Gilson Opals are the most well-known lab-created opals. Synthetic opals generally show brighter colors, are larger, and have a more ordered array of colors. Numerous subgrains in synthetic opals produce a delicate snakeskin pattern.

Imitation Opals are made with colored tinsel set in clear plastic or epoxy. They’re generally not convincing to the untrained eye.

What Are the Different Types of Opals? | Barbara Michelle Jacobs Blog

Doublet Opal

Doublets and Triplets are partially man-made stones that imitate black opals. Doublets and triplets consist of a slice of opal attached to a dark backing. In addition to being attached to a dark backing, triplets have a clear quartz or glass capping to magnify and protect the stone while giving it a rounded appearance.

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Photos: James St. John via Flickr, Pixabay, Biro Opal, Wikimedia Commons

Posted in gem facts, gem lore, gemology, gems, informative, opal

December Birthstone: Zircon

Posted on December 15, 2015 by Mary Hood | 0 Comments

Zircon is one of the birthstones associated with December (the others are turquoise and Tanzanite). “Zircon” may be derived from the Persian word “zargun,” meaning “gold-colored.” The word may also be derived from the Arabic word “zarkun,” meaning “cinnabar” or “vermillion.”

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Posted in birthstones, cubic zirconia, december, gem facts, gem lore, zircon