Grading

Dive into GIA’s Pearl Expertise

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Dive into GIA’s Pearl Expertise

When it comes to knowing the identity and quality of your pearls, count on GIA as your independent pearl experts.

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Brought To You By GIA


Pearls are marvels of nature that form in a variety of mollusks and exist in a stunning array of colors and quality. They have been prized for thousands of years, revered as tears of the gods by the ancient Persians and used as talismans against fire by the ancient Chinese. To many, they symbolize perfection because they emerge fully formed from mollusks and do not require faceting or other major human intervention to finish them.
 
At GIA, we have made it our mission to study the science behind pearl’s beauty. We have pursued pearl knowledge and research since 1949, embarking on field gemology trips to bodies of water around the globe, from the rivers of Mississippi to the bays of Vietnam to the oceans of Australia and Tahiti. Auction houses, museums and collectors entrust us with examining rare specimens such as the Empress Eugenie pearls and the Saffron Dragon melo pearl. We issue pearl reports that are recognized around the world.

When it comes to knowing the identity and quality of your pearls, you can count on us, your independent pearl experts.
 

Identifying Pearls

Natural or Cultured?
Natural pearls form when the mantle of a mollusk is irritated by a foreign “intruder.” The mollusk secretes calcium carbonate, often in the form of nacre, to protect itself from the irritant. As the mollusk deposits more and more layers, a pearl forms. Natural pearls are rare. Only roughly 1 in 10,000 mollusks will produce a pearl, and of those produced, most are small and irregular in shape. Large natural pearls that are round or drop shaped are incredibly valuable. In the past, many of these pearls, such as La Peregrina or the Baroda pearls, were owned by royalty and have significant historical value. Natural pearls are so valuable that in 1917, the millionaire Morton Plant traded his Fifth Avenue mansion for a double strand of natural pearls by Cartier. 
 
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The Baroda Pearl Necklace features select natural pearls from a necklace once owned by the Indian Maharajas of Baroda. Photo © Christie's Images


Cultured pearls form through human intervention when a nucleus is inserted into a mollusk to spur pearl growth. The nucleus is often a round shell bead, which helps determine the size and shape of the pearl that forms. The most common cultured nacreous pearls are South Sea, Tahitian, akoya and freshwater, each of which forms in a different type of mollusk and has distinct characteristics. 
 
Telling natural and cultured pearls apart often requires testing in a gemological laboratory with sophisticated instruments. GIA scientists determine the identity of pearls by using X-ray techniques such as real-time microradiography (RTX) and X-ray computed microtomography (μ-CT) to analyze a pearl's internal structure.
 
Nacreous pearls are the most popular pearl type on the market, but many natural non-nacreous pearls such as melo pearls and conch pearls are also rare and highly-treasured.  
 
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This natural pearl has an organic-looking core (thought to be coral) seen here through X-ray computed microtomography.

Classifying Pearls 

GIA classifies pearls using the GIA 7 Pearl Value Factors™, which were created to describe the quality of nacreous pearls in a systematic way that everyone can understand. These factors include size, shape, color, luster, surface, nacre, and matching. 
 
Pearl’s mysterious beauty can be complex to analyze. Did you know that color alone includes bodycolor, overtone and orient? GIA experts compare your pearls to a set of carefully pre-selected pearl masters to determine color and classify its other value factors. All pearls submitted to our laboratories are independently analyzed by two different teams of GIA pearl experts to ensure a precise and objective evaluation.
 

GIA Pearl Reports

GIA is an independent nonprofit committed to serving the public through the relentless pursuit of research, education, and laboratory innovation. We set standards for evaluating gem quality and issue reports that are recognized and respected worldwide. When you have a GIA report, you can rest assured that you know the identity and quality of your gem. We currently offer three different pearl reports:
 
GIA Pearl Identification Report
This report covers the quantity, weight, shape, color, overtone, identity (natural or cultured), mollusk origin type (when determinable) and formation environment of your pearl(s), as well as any detectable treatments. It also includes a digital image and is available for any pearls, loose, mounted, or strung.
 
GIA Pearl Identification and Classification Report
This comprehensive report contains all the information of an Identification Report plus quality classification such as luster, surface and matching (if applicable). It is available for loose, mounted or strung untreated nacreous pearls. 
 
GIA Cultured Pearl Classification Report
This report for cultured akoya, South Sea or Tahitian pearls includes a detailed classification of your pearls based on the GIA 7 Pearl Value Factors™ (size, shape, color, luster, surface, nacre and matching). 
 
The queen of gems and the gem of queens, pearls have been beloved throughout history and are at the forefront of many trends in both women’s and men’s jewelry. Whether natural or cultured, their quality can vary widely. Some pearls even undergo treatments such as dyeing that can affect their value dramatically. Your stunning jewels deserve the expertise of GIA’s scientists. Know you’re getting the best when you purchase pearls that come with a GIA Pearl Report. 

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