Pearl Grading Criteria
Size, shape, color, luster, and purity determine the value of a PEARL:
Pearl SizeThe size is determined by the shortest diameter and usually varies between 3.5 and 14 mm. Some Tahitian cultured pearls reach 16 mm or, in rare cases, even 18 mm. The largest pearl found to date has a diameter of 21 mm.
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Pearl ShapeThe most coveted form, the round or perfectly spherical pearl, is also the rarest. But there are many other shapes, all possessing their own charm. They are usually classified as: "semi-round," a slightly deformed sphere; "semi-baroque," which shows an axis of rotation and comes in button, oval, drop, and pear shapes; and "circular," which has grooves over more than a third of its surface.
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Pearl ColorAll color variations from light white to pink, golden, and bluish-black occur. The most expensive colors are peacock green, aubergine purple, and navy blue, in addition to all shades of gray and those with an iridescent surface. The color nuances are created by the refraction of light on the pearl's surface.
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Pearl LusterThe luster of a pearl depends on its brilliance, meaning its ability to reflect light. In very good pearls, this characteristic can create a mirror effect. Pearl luster ranges from perfect brilliance to dull opacity.
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Pearl PurityAs with all pearls, the surface condition helps determine the value. Quality is assessed by the position and number of blemishes such as bumps, scratches, and spots, all of which reduce the pearl's value. Flawless specimens are rare.
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Nacre ThicknessThe more layers of nacre a pearl has, the more durable this jewel is. The thickness of the nacre layer is significantly influenced by the duration of pearl growth and the water temperature.
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Pearl QualityIs it exclusively beauty in the eye of the beholder, or can it be measured objectively? When it comes to choosing cultured pearls, the customer must rely on both subjective and objective criteria.
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Shape, size, quality, and rarity of the jewel are all characteristics that can be objectively evaluated. For example, the rounder and larger a cultured pearl is, the more valuable it is. Surface condition also plays a large role in value determination; the fewer imperfections, the better. Luster is another factor. Normally, a pearl of the highest quality is brilliant and reflects light well, however, for gray pearls, a medium or light luster is sometimes preferred.
