The Pearl Page

by

Jed G. Archuleta

http://emporia.edu/earthsci/amber/go340/students/archuleta/index.htm

This page was created as a student project at Emporia State University in the Spring 2003 semester. The project was in partial completion of an online Gemstones and Gemology course.


Pearls have been admired and collected since the time of earliest recorded history. Virtually every culture has embraced their beauty and mystery. The intent of this webpage is to provide some insight into what makes a pearl a pearl. In doing so, several locations and techniques for pearl production will be taken into account. A wide variety of colors, shapes, and presentations will be discussed as well as what some of these factors may indicate about a specific pearl. I will touch on the general ideas of valuation for pearls. While reading this page over, I hope that I will provide you with a small portion of what makes the pearl a unique and truely fascinating gemstone.


Table of Contents

South Sea pearl necklace image taken from Allé Jewelry (multicolor.jpg)
South Sea pearl necklace
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Image taken from Allé Jewelry


Pearl Characteristics

Pearls are naturally occurring organic gemstones that are created inside the shells of certain types of mollusks. They are formed by the concentric accumulation of nacre around an irritant inside the mollusks' shell. This nacre is composed of a mixture of the mineral aragonite and an organic horn substance called conchiolin. This concentric layering creates a characteristic luster and play of color and light. This optical effect can also be seen in mother-of-pearl specimens, which are typically the inner layer of nacre lining the inside of a mollusk's shell. Pearls have several characteristic features that their value is derived from. These characteristics are as follows:


Pearl Types


Pearl Culture and Production

The culture and production of pearls has been taking place since as early as the fifth century B.C.(Landman, et al, p.154) The Chinese, in this time period, deposited various objects between the shell and mantle of various freshwater pearl mussels and returned them to the water. In a years time or so, they would return to the river to find their objects covered with mother-of-pearl. This is not so different from the cultivation processes of today, with the exception of the the scale and attention to environmental factors. Today's methods were developed by a Japanese man by the name of Kokichi Mikimoto at the turn of the nineteenth century. An online account of the development of this technique can be viewed at http://vjd.it/06per/perle/01sto/1100/eindex.asp.

It is important to note that nearly all pearls in the market are cultured pearls. Natural pearls are truely a rarity. The method of pearl production varies little from one area to the next with the only main differences resting in optimum temperatures, pH, trace element concentration, and cultivation time. The most difficult part of pearl culturization is determining the time that the pearls should be left to develop. As I have said previously, thicker nacre produces a larger, more lustrous pearl. However, a longer cultivation period also means a greater chance for outside inclusions or contaminates. The truth is, there is no correct answer to this puzzle. Pearl culture professionals take a risk with every harvest, but as they gain more experience, with both the environments and the species, optimum times and conditions are reached for maximum profitability. A brief overview of an Austrailian culturing method can be viewed at http://costellos.com.au/pearls/cultivation.html.

Some of the leading pearl producing nations are listed below as well as the types of pearls that they produce.

China is the leading producer of both freshwater and seawater pearls. Most Akoya pearls in the range of 6 mm or less come from China. Very few other saltwater pearl types are being cultivated in this area. Freshwater pearls are cultured in a variety of styles, ranging in color and shape. A fairly new product in this market has been the "all-nacre" pearl which has a nacre "seed" implanted as the nucleus.

Australia is the world's largest producer of South Sea pearls. They also produce a local variety of pearl known as "keshi" pearls. These pearls are highly regarded for their thick nacre, and thus, they are cultivated within the oysters for a longer period of time, sometimes up to three years. Colors are generally in the white to cream range, but occassionally black pearls are produced.

Japan cultures the Akoya, a primary seawater pearl. It has been the site for the production of the most lustrous pearl of its kind. The thick nacre layer is again responsible for this, but in this instance it is the increased nacre production rate that effects the layering. Japan has begun to culture black pearls, but they are much smaller than those produced in Tahiti and French Polynesia.

Tahiti is known for its exotic black pearls. Most of these pearls lie in the gunmetal gray range, but nearly all display a rich orient. These pearls can be found in smaller supply in nearly every color and orient from greens to purples. This high quality orient is a by-product of these pearls' extremely thick nacre. In order for proper formation, they must be cultured for a period of two to three years.

The United States was the first country to develop the process of culturing a new type of pearl: the American freshwater cultured pearl. These pearls are produced and marketed in a number of ways. Many baroque pearls, as well as mabe' and blister pearls come from these methods. These pearls have a very rich luster and orient and come in a variety of colors and shapes.


Final Thought

As you can see, pearls are, within the details, nearly as mysterious and uncontrollable to us today as they were in ancient times. This, in large part, is why they continue to be popular and valued today. Their iridescence and orient can be roughly mimicked, but never matched. These qualities and characteristics of a pearl's beauty can only be achieved through patience, maintenance, and a little bit of luck.


Links and References


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