The Different Criteria for Pearl Valuation
Pearls are the pearly concretions secreted inside oysters. The trade description, Tahiti Cultured Pearl, is exclusively reserved for pearls produced by a graft of the black-lipped Pinctada Margaritifera oyster of the Cumingui variety. They possess a continuous pearly layer that does not reveal its nucleus, even through transparency.
Pearls are characterized by a diversity of shapes, sizes, surface quality, luster and several shades of natural colors.
The pearl’s shape determines its value. Pearl shapes can be divided into differents main groups:
Following are the groups in order of value:
: perfect or almost-perfect spheres with a diameter-variation rate lower than 2%. Round pearls are highly prized but rare, thus the most sought-after pearls.
slightly deformed spheres with a diameter-variation rate of between 2% and 5%.
pearls exhibiting at least one axis of rotation. They are divided into several families:
: semi-baroques of ovoid form.
: semi-baroques with at least one flat face.
- Oval Shapes
: semi-baroques elliptical in shape with an axis of revolution and a perpendicular symmetry plane.
- Pear Shapes
irregular shapes without any axis of revolution. They inspire the creation of original jewelry.
pearls characterized by one or more concentric circles.
The round pearl has always been considered as the most expensive and the most recognized pearl shape.
Choosing a pearl that is less round in shape offers a good compromise when it comes to buying a less expensive pearl.
Size is determined by dropping the pearl through a series of circular sieves. It is measured in increments of 0.5 mm.
The diameter of the Tahiti Cultured Pearl is usually between 7.5 to 16 mm with rarer ones going up to 18 mm. Size has a significant impact on the price. The size depends on the largeness of the nucleus and the thickness of the mother-of-pearl layers secreted by the oyster.
A pearl’s “skin” can be appraised by observing the characteristics of its surface. Surface characteristics include all alterations on the pearl’s surface such as punctures, stripes, deposits, wrinkles and outgrowths.
Parliament regulation No. 2001-88 APF of July 12, 2001 defines four basic qualities—A, B, C, D.
Pearls with at most one visible flaw or a localized group of imperfections concentrated on less than 10% of its surface. They have a very beautiful luster.
Pearls presenting some imperfections over a maximum of 30% of its surface. Good or average luster.
Pearls presenting imperfections over at most 60% of its surface. Average luster.
Pearls presenting imperfections over more than 60% of its surface, or pearls without luster
One of the most important indications of a pearl’s quality is the luster. It is defined as the capacity of the pearl to reflect light. A pearl with a high luster will be very shiny and reflect light like a mirror, whereas a pearl with a low luster will be quite milky.
The luster is determined by the quality of the mother-of-pearl, its transparency and its thickness. Factors affecting the quality of the mother-of-pearl include the cultivation location, the oyster’s health, the length of cultivation, pollution and the type of oyster used.
Pearls come in a wide range of colors. Lightly-colored pearls come in shades of white, pink, silver, gold and blue. Darker pearls go from peacock green (fly wing) to aubergine purple to all shades of grey.
The choice of pearl color is essentially a matter of personal taste. Nevertheless, some colors are especially rare or coveted and are therefore worth more. These include for example, rose white, silvery white, pale gold and peacock green. A pearl’s color is therefore not a criterion of quality but rather, it is a subjective criterion.