Welcome to Pearl school 101


THE INTERNATIONAL STANDARDS FOR TAHITIAN BLACK PEARLS

These are exciting years for the Tahitian black pearls. After decades of struggle, black pearls are finally being produced in sufficient quantity to attract the attention of consumers throughout the world. Along with this attention has come an increasing demand for international standards in pricing the black pearl. The purpose of this guide is to introduce you to the criteria currently
used to appraise black pearls and, hopefully, to provide some common sense advise to help you to select the Tahitian black pearl best for you.
Tahitian black pearls, like Japanese white pearls and Australian south sea pearls, are cultured pearls produced by the Mise-Nishikawa technique, a method developed independently by Tatsuhei Mise and Tokichi Nishikawa in the early 1900's. The Mise-Nishikawa method involves seeding a small piece of tissue along with a nucleus into a pearl oyster. The nucleus, a small bead of mother-of-pearl (MOP) machined to be perfectly round and smooth, serves as the center of the pearl to be produced. The tissue, made of epithelial cells from a donor oyster, grows around the nucleus and secretes MOP that accumulates on the nucleus in micron-thin layers. These layers of MOP, plus the bead at the center, constitute a cultured pearl. The species of oyster used in the process determines what type of pearl is produced. Tahitian black pearls are produced by the black-lipped pearl oyster, Pinctada margaritafera.
After harvest, black pearls are appraised by five criteria: Orient, Form, Surface, Size, and Color. The remainder of this guide will explain how the criteria are applied and how they affect the price of a black pearl. Although an appraisal is normally done on unset pearls, the same standards may be applied to pearls that have been set in jewelry.

ORIENT: THE GREATER THE RADIANCE, THE HIGHER THE VALUE

QUALITY: SHINE: INNER-LAYER REFLECTION:
PLUS Excellent No irregularity
NORMAL Very Good Some irregularity allowed
MINUS Good Irregularity detracts from appearance
REJECT Dull (Not important)

Luster, or Orient*, is the quality of shining by reflected light. Luster describes the radiance that results from the interaction of light with the crystalline structure of a pearl. There are two components to luster. The surface must have a mirror-like shine. Black pearls should never have a dull surface. Luster also has an inner-layer quality that provides much of the radiance. Irregularities in the inner layers, described as waves or hammer marks, reduce the luster as light is refracted and not reflected. Black pearls are famous for their luster and even a pearl with irregularities in the inner layers must have good shine and radiance.

* Orient is the original term for this quality, but the current trend is to use Luster. Orient and Luster are synonymous.

FORM: THE MORE ROUND, THE MORE SYMMETRICAL, THE HIGHER THE VALUE

GRADE: DESCRIPTION:
R ROUND < 2% out of round. Appears round on visual inspection
SR SEMI-ROUND < 5% out of round Slight deformation visible
SB SEMI-BAROQUE > 5% out of round Symmetrical but not round
Ex.: Tear-Drops, Pears, Buttons, Ovals
BAR BAROQUE Irregular, no symmetry to shape
CIR CIRCLE Distinctive rings around pearl
Any shape from round to baroque
The form, or shape, of a pearl is judged by roundness and symmetry. Round pearls, followed closely by Semi-round, are valued highest because they are the most difficult form to produce and because they are considered the ideal shape for pearls. Semi-baroque pearls are generally less expensive except for SB Drop and Pear shapes. Drops and Pears are highly valued for their symmetry and priced with SR pearls. Baroque pearls are the least expensive. Circle pearls are graded as a form of pearl due to a standard accepted in the pearling industry. The circling is not considered a surface flaw. Circle pearls are valued by their actual shape and amount of circling.
SURFACE: THE CLEANER THE SURFACE, THE HIGHER THE VALUE

GRADE: FLAWS: MINIMUM CLEAN:
*GEM 0 100%
A 1-2 90%
B 2-5 67%
C >5 33%
D >5 <33%

The surface is graded by the quantity of flaws over the pearl. The most common flaws are small pits and rays that blemish the surface. The number of flaws is used as a guideline for grading a pearl, but it is the distribution of flaws that truly determines the grade and the value. The amount of clean surface is most important because it affects the general appearance of the pearl and the type of jewelry for which the pearl is suitable.
* Some producers group Gem with Grade A. I prefer to separate them due to the rarity of Gems and their higher retail value.

SIZE: THE LARGER THE DIAMETER, THE HIGHER THE VALUE

SIZE: DIAMETER OF PEARL:
LARGE > 11.5 MM
AVERAGE 9.5 - 11.5 MM
SMALL 8.0 - 9.5 MM

Black pearls can be as small as 8 mm and as large as 20 mm. Size is measured to the nearest tenth of a millimeter as the smallest diameter of the pearl for Round and Semi-Round pearls, and as the smallest diameter of the main body of the pearl for SB, BAR, and CIR pearls. Price increases continuously with size. Larger pearls are more expensive because the volume of MOP increases greatly with size which causes larger pearls to be more difficult to produce. Volume should not be confused with thickness of MOP. The thickness of MOP should be about the same regardless of the size of the pearl.

COLOR: THE RARER THE COLOR, THE HIGHER THE VALUE

DESCRIPTION: HUE: CHROMA:
RARE RAINBOW, AUBERGINE, HIGH
FLY-WING GREEN
STANDARD GREEN, BLUE, VIOLET HIGH
LIGHT WHITE, GRAY, SILVER LOW

Black pearls are rarely black and receive their name not from their color, but from the species of oyster that produces them, the black-lipped pearl oyster. Black pearls actually vary across a large range of colors. Color is appraised by hue and chroma, the basic properties of color. Hue defines the spectral region that gives a color its name while chroma defines the purity of color which is the absence of white or grey. Chroma is best understood as the intensity of a distinctive hue. Color does not affect value for the majority of black pearls since most black pearls have a distinctive hue and high chroma. Color affects price only under two unusual conditions. Black pearls with rare hues will be priced higher. And, pearls with low chroma (white or grey prevalent) will be priced lower.
SELECTING A BLACK PEARL: QUALITY, GRADE, AND PRICE
I suggest that the first step toward choosing a black pearl is to organize the appraisal criteria into a less technical pattern, based on more commonly used terms. I organize the criteria to emphasize four guidelines to use while selecting a black pearl.

QUALITY = LUSTER
GRADE = FORM + SURFACE
PRICE = QUALITY + GRADE + SIZE + COLOR

First, ALWAYS BUY QUALITY. Luster, or Orient, defines a pearl's quality. I admit that other producer's of pearls may disagree, and claim that quality is defined by both luster and surface grade. In response, I offer the following from Webster 's New World Dictionary Of The American Language:
ORIENT: noun, the quality that determines a pearl's value; luster. A pearl of high quality. ORIENT: adj, brilliant, shining, precious: originally of pearls, now more general....
I prefer to remain with this definition. Luster is the most important criterion for judging a pearl of quality and value. No matter if the pearl is a perfect, Round A, 18 mm, with beautiful green color, if it is dull and lacks luster, it is of little value. Never sacrifice luster when choosing a black pearl.
Second, CHOOSE GRADE FOR JEWELRY. Black pearls are graded by their form and surface while quality should be judged by the luster. You are not sacrificing quality when you decide what grade of pearl to buy. The grade of pearl should be most heavily influenced by the style of jewelry for which the pearl is intended. For example, Round B pearls are excellent for rings since only two-thirds of a pearl is visible after it is set in a ring.
Third, ADJUST PRICE BY SIZE. The price of a black pearl is the commercial value determined by market forces that demand black pearls of certain quality, grade, size, and color. The quality and grade of a pearl, the most important criteria, determine only part of its price. Size has nothing to do with quality or grade, but strongly affects price. The simplest way to adjust the price is to start with a size of pearl that matches your budget.
Fourth, PICK THE COLOR YOU PREFER. Color also has nothing to do with quality or grade. The various colors of black pearls provide an enormous selection while only the rare colors affect price. I will never understand why some people say that black pearls should be green, as green pearls represent only a portion of the beautiful colors available. Choose the color that you prefer and do not be influenced by salespeople that may have an agenda to sell you the most expensive pearl.