The Unusual Pearls

for

GO 340 Gemstones & Gemology

by Harry Jenkins

Emporia State University
Emporia, Kansas USA
Spring 2010 Semester

Table of Contents

Introduction Abalone Pearl
Conch Pearl Tahitian Pearl
Blister Pearl Keshi Pearl
Melo Melo Cortez Pearl
Lion's Paw Pearls Conclusion
References and Related Links


Introduction

Pearls are a fascinating gem that can be spectacular right out the shell. Pearls are found in many parts of the world and in many different species of mollusks. They have been collected and coveted forever by divers and royalty around the world. When most people think of a pearl, the image that might come to mind is of a pure white perfectly rounded object. Yet, this is what unusual pearls is all about... the often found irregular shaped, sized, colored pearls that occur in many different environments. After reading this page I hope you will be able to see how unique and beautiful these are pearls are as well as the ideal that might come to mind!

Physical Properties Common to all Pearls

Color: Varys, multi-colored to black Streak: White
Moh's Hardness: 2.5-4.5 Fracture: Uneven
Density: 2.60-2.85 Cleavage: None
Dispersion: None Refraction index: 1.52-1.66; black: 1.53-1.69
Chemical Composition: Calcium
carbonate + Organic Substances + water
Crystal system: Orthorhombic

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The Conch Pearl


Image taken from
Modern Jeweler-Conch
Pearls by David Federman

The conch shell has a 7 to 12 inches high shell and is a white meat mollusk. The raspberry red to pink colored pearl is a unique pearls produce by the gastropod organism. While some may believe 20% out of 3000 of the pink pearls harvested from conch shells are gem quality, Federman stated the ratio was one in ten thousand (Modern Jeweler-Conch Pearls). Conch pearls are harvested from gastropod mollusks living in warm waters of Bahamas, Florida and Yucatán. In order to harvest the pearl, the organism must die; the conch's spiral shell makes it impossible to reach the area where pearls without killing the organism. The pearl has white markings just beneath the surface, exhibits chatoyancy around the edge, and fades when exposed to sunlight. Pearls vary in size and shape, with color variation of pink, yellow, and white. Most common shapes are baroque and oval with a diameter of 3 millimeters and smaller.

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Blister Pearls

Blister Pearls are half a pearl, produce purely by coincidence. They are pearls that form on the inside of the oyster’s shell opposed to inside the living organism itself. Blister Pearls have flat backs that face towards theoutside of the shell. To culture the blister pearls a drill is use to release it from the inner shell. The nucleus is removed and replaced with resin; the back is then replaced with a piece of mother-of–pearl.

Image right taken from Blister Pearls, altius directory.

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Tahitian Pearls


Tahitian Pearl
taken from KariPearls.com.

Tahitian pearls are one of the most exotic pearls around which look black but can be seen in many different over tone of dark-back to green. Each of these Tahitian pearls are unique in every way. These South Sea pearls are cultured from Pinctada Margaritifera oyster or the black-lipped pearl oyster. Tahitian pearls are seen in a vary of colors from a dark jet black to a green or pale gray. Unlike other species of bivalves, Pintctada Margaritifera do not live long after nacre has been implanted to culture the pearl. Shapes of Tahitian pearls are round to semi-round and range greatly in size.

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Melo Melo Pearls

Melo snails can range in size weighing as much as 17 pounds and produce a pearls with a diameter of 2 centimeters (PalaGems, http://www.palagems.com/melo.htm). “Melo shell are also used as souvenirs for tourists: melo boats, melo horn, melo horn lamps...”(Pardieu, 2009). Melo Pearls are considered unusual because they only come from Melo Melo marine snail in Southeast Asia. Melo pearls are usually round and large ranging in a variety of colors of colors from tan and dark brown. All attempts to culture melo pearls have failed.


Image of Melo Pearls taken from
Palagem.com
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Lion's Paw Pearls

The Scallop pearl was recently discovered in 2000. These pearls come from a bivalve shaped like a lion's paw and some have named the organism Mano de Leon, which when translated means hand of the lion. Scallop pearls are found in marine bivalve scallop from Baja, California.

Image left, Scallop Pearls, taken from Pearls.com.

These pearls form within the scallop’s body, between the mantle and the shell. They are unusual because of a semi-metallic to chatoyant luster and deep royal purple color. Shapes include ovals, drops, and buttons and the pearl is commonly found up to a size of 40 carats.

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Abalone Pearls

Abalone pearls are founded in the mollusk Haliotis. Abalone pearls are mostly found in its horn shape. Abalone pearls have a mixture of colors from lavender, orange, pink, silver, and blues. Due to the Haliotis anatomy culturing abalone pearls are very difficult. Much care has to be taken during the culturing process. The species Haliotis are hemophiliacs so if a nucleus is implanted in the same fashion to mollusk the organism will bleed to death.

To see a stunning image of abalone pearls, copyrighted by Eyris Blue Pearl Company from Germany, visit www.selectraders.co.uk/abalone-pearls-2.html.


Image taken from
www.allnaturalpearls.com/abalone.htm.
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Keshi Pearls


Keshi Pearls taken from Luxury Faceted Gemstones.

The term keshi pearls was first used in early 20th century Japan to describe natural seed pearls (Canizzaro, Sarah). Keshi pearls are created when the mollusk tries to reject and expel the implanted nucleus. At first look, Keshi pearls do not resemble typical pearls. They are termed reborn or cornflake pearls, which are made up of pure nacre. This results in a high luster. Keshi pearls are becoming rare because pearl farmers use x-rays to examine oysters now and if the nucleus has been expelled, it is re-implanted. Keshi pearls are never enhanced, only washed in water and soaked in mineral oil.

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Cortez Pearls

CortezPearls are a registered trademark pearl, which are "rare saltwater cultured pearls from the rainbow-lipped Pteria sterna oyster, native to Mexico's Sea of Cortez" (http://www.columbiagemhouse.com/cortezPearls.html). Natural pearls harvested from oysters in the Sea of Cortez were admired by Captain Fortun Jimenez in 1533 when he visited what he called the Sea of Pearls (http://www.columbiagemhouse.com/cortezPearls.html). The culturing industry is centered around Bacochibampo Bay, near Guaymas, Mexico.

In recent years, the Concha Nácar oyster is used to produce blister pearls as well. These Cortez pearls have a uniquqe luster and iridescence. with varied of colors from dark champagne to charcoal (http://www.columbiagemhouse.com/cortezPearls.html). Cortez pearls resemble abalone or Tahitian black pearls, but are easily recognized by their distinct red fluorescence under long-wave UV light (http://www.columbiagemhouse.com/cortezPearls.html).

There are great pictures and information online for these pearls at:

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Conclusions

Pearls are known to represent elegance and beauty. They require no enhancement and are beautiful right out the oyster, mollusk or snail. They can also be given as a gift on the first wedding anniversary and are traditional at the wedding ceremony. There are many different ancient folklore that explains how the stunning objects are formed. Most unusual pearls are created from unusual creatures. These include the conch pearl with its beautiful chatoyancy to the 17 pound snail that produces the Melo pearl; from the dark champagne color of Cortez pearls to the abalone pearl. Like the often thought of white pearl, these unusual pearls with unique colors are just as beautiful and elegant.

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References and Related Links

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About This Webpage

This website was created by Harry Jenkins, May 2010. It fulfills an assignment for a gemstone and gemology course from Emporia State University, Earth Science Department, http://www.emporia.edu/earthsci/earthsci.htm. For questions and comments, email hjenkins@emporia.edu.

Return to other student webpage examples at www.emporia.edu/earthsci/amber/go340/students/stupages.htm.

Images from www.emporia.edu/saf/news/spotlight/s09_papahornet.htm"