The Gemological Institute of America (GIA) is an independent body devoted to research and higher education in gemology. They are an institution of learning, research, and development. The GIA is recognized internationally as the foremost authority in Gemology and continue to strive to educate gemologists, jewellers, manufacturers, and all those involved in the jewellery trade, in addition to the public.

The GIA developed a system of evaluating pearls that has been adopted and adapted for use internationally. The GIA system is based on seven value factors: pearl species, shape, surface, color, nacre thickness, matching, and luster. Each pearl type has its own range of possibilities for each value factor. A pearl's worth depends on how the combination of these value factors are present.

Because there is not a sole grading system that has been accepted, and is used consistently by all members of the trade around the world, it is particularly important for the consumer to be educated about the product and the actual pearl attributes being observed. The most common grading scale used for pearls internationally is the A-AAA system. Though, most retailers modify the scale to be more specific about the quality of a product being sold. Regardless, a reputable jeweller will fully disclose the grading system they use and ensure it is understood.

All grading systems aside, what is applied consistently internationally with regard to grading pearls is two fold:

Luster	The higher the luster and sharper the reflection, the greater the value.
Shape	Rarity and tradition make round pearls the most valuable.
Inclusions	The fewer the inclusions and blemishing, the greater the value.
Matching	On a multi-pearl piece or set, the more exact the matching across all attributes, the greater the value.
Nacre	The smoother and thicker the nacre, the greater the value.
Size	All other factors being equal, the larger the pearl, the greater the value.
Colour	Rarity of a colour will increase the value of a pearl(s), though colour tends to be subjective and influenced moreso by consumer trends.

Recognition of a Distinctivly Higher Quality Pearl
Peculiar to a Specific Region

China	best quality Freshwater Cultured Pearls
Japan	best quality Akoya Saltwater Cultured Pearls
French Polynesia	best quality Black Tahitian South Sea Cultured Pearls
Indonesia	best quality Golden South Sea Cultured Pearls
Australia	best quality White South Sea Cultured Pearls