South Sea pearls are the largest and rarest cultured pearls on the market, which makes understanding South Sea pearls grading essential for buyers new to this pearl type. Unlike mass-market pearls, small differences in luster, surface quality, and nacre thickness can dramatically affect value and long-term beauty.

With over 20 years in the jewelry industry specializing in cultured pearls, my South Sea Pearls Grading Guide focuses on both White and Golden South Sea pearls, and explains how Pure Pearls’ A–AAAA grading scale is applied in practice when evaluating and valuing pearls. Using real-life photography of pearls in our vaults, side-by-side comparisons, and plenty of visual charts that highlight grading benchmarks and pricing differences, this guide shows what you can realistically expect to see at each quality level. All grading terminology is aligned with standards defined by the Gemological Institute of America (GIA).

You can read the guide from start to finish for a complete foundation, or use the table of contents to jump directly to the grading factors or quality levels most relevant to your buying decision.

Budgeting wisely means deciding where to compromise and where not to. For example, an 8–10mm AAA-quality South Sea pearl strand can be found for under $8,000, offering exceptional luster and clean surfaces at a more approachable price point. Move up to 11–13mm large South Sea pearls, and prices typically begin around $12,000 to $15,000, assuming similar quality factors. Setting your budget should always account for luster and overall quality first, with size adjusted to fit your comfort zone.

Shape also plays a big role in value.Round South Sea pearls are the most traditional and command the highest prices due to the difficulty of matching pearls perfectly. Baroque, slightly off-round or button-shape pearls, however, can offer incredible savings. These pearls still have beautiful luster and presence, but their unique shapes allow buyers to enjoy larger sizes or higher quality at a significantly lower cost.

Luster, Luster, LUSTER. And natural pearl colors found nowhere else on Earth. These two attributes are primarily what makes South Sea pearls valuable and coveted by pearl connoisseurs the world over.

White and Golden South Sea pearls are known to have the thickest nacre layers of all cultured saltwater pearl types, averaging between 2.0-4.0mm thick, or more.

Almost universally described by pearlers as “satiny” in look, South Sea pearl luster is softer in appearance than that of the Japanese Akoya Pearls.

South Sea pearls radiate a gorgeous “glow” that appears to emanate from within, rather than the harder “mirror-like shine” that Akoya pearls are famous for.

That’s not to say that South Sea pearls can’t feature very bright, very sharp luster – they can and do. Check out this picture that showcases a pair of Golden South Sea Drops with almost Metallic levels of luster (WOW)..

Luster and nacre quality are two of the most important indicators of a South Sea pearl’s beauty and value. High luster comes from thick, well-formed nacre layers, which allow light to reflect sharply and create bright, mirror-like reflections. Pearls with a soft or hazy glow typically have thinner or less compacted nacre layers and are considered lower quality.

South Sea pearl nacre thickness also plays a key role in how a pearl ages over time. Thicker nacre improves durability and helps a pearl maintain its appearance for decades, making it especially important for fine jewelry and heirloom pieces. In South Sea pearls, strong luster paired with substantial nacre is a hallmark of premium grading.

Like every other cultured pearl variety out there, the visual phenomenon of body color, overtone and luster are due to the compaction and smoothness of the pearl's crystalline nacre layers.

White and Golden South Sea pearls are both nucleated using a perfectly round mother-of-pearl bead nucleus. The nucleus is surgically placed into the gonad of the oyster, along with a tiny, 1.0mm square piece of donor mantle tissue from a different oyster. The incision is covered over and the oyster is placed into an “after surgery” tank for a few days while it heals from the procedure.

After a short time, the bead nucleus stimulates the formation of a pearl sac, which envelopes the nucleus in a loose “purse” and the oyster begins secreting nacre.

This continues on for about 2-3 years, as the oyster continuously covers the interior bead nucleus with thousands of concentric layers of nacre and conchiolin, eventually forming a pearl - hopefully a perfectly round one.

Some definitions you should know are:

The tighter and more compact the aragonite and conchiolin layers are, the more intense the luster, color and orient you will perceive on the pearl’s surface.

Now that you’re a bit more familiar with how and why these various elements combine to create the visual phenomenon of "Wow!" to us humans, we can move onto learning about the A-AAAA South Sea Pearl Grading Scale that Pure uses.

The breakdown below examines each pearl grade, and lays out specific benchmarks that South Sea pearls must meet in order to "make the grade".

No South Sea pearls grading guide would be complete without showing you what the pearls look like at each grading benchmark. The images depicted in these grading breakdowns include a mix of perfect round and off-round/button and baroque South Sea pearl necklaces.

Keep in mind that baroque or drop-shaped pearls are graded using the same A-AAAA scale as perfectly round pearls.

In addition to luster, color and surface quality, for baroque and semi-baroque pearls, the symmetry of shapes and shape-matching play very important roles in determining South Sea pearl quality.

The South Sea pearl grading factors used here are luster, surface quality, nacre thickness, shape, color, and matching. Size doesn't really play a roll in grading, as pearls can be any size and still AAAA quality. Instead, size comes into play when pearls are priced, with larger pearls being rarer and thus more valuable.

With Golden South Sea pearl grading, color also plays an important role.

The best rule of thumb to go by is: the deeper the golden color, the rarer and more valuable the pearls are, all other quality factors being equal.

Cultured pearls will never be as flawlessly perfect as a synthetic glass or plastic bead can be – nor should you want them to be. 

Mother Nature always signs her creations, and these unique inclusions and marks can act as a built-in ID system that marks the pearls as yours and yours alone.

Pure does not offer any AA+ quality round loose or matched South Sea pearl pairs; all round pearl earrings, pearl pendants and pearl rings featured on Pure are AAA Quality minimum.

We use this quality control policy to make sure that each pendant, pair of earrings, or pearl ring that leaves our office will set clean in front and the sides of the pearl, so you’re only showing off pure gorgeousness, and NOT blemishes.

As with all precious gemstones, it pays to remember: price isn’t everything.

Pure’s “AAA Quality Minimum” policy may make our prices appear less competitive at first glance, but this standard exists for a reason. By refusing to work with lower-grade pearls, we ensure that every piece meets a baseline of strong luster, solid nacre, and clean overall appearance. This commitment results in jewelry that simply looks better when worn and continues to look beautiful over time.

This matters especially when it comes to South Sea pearl earrings quality, where close-up viewing and symmetry are critical. Earrings demand well-matched pearls with bright luster and minimal visible blemishes, and lower grades often fall short in these areas.

By starting at AAA quality, we create earrings, pendants and pearl rings that feel refined, balanced, and satisfying from the first wear. In the long run, this approach leads to prettier pearl jewelry, greater confidence in each purchase, and happier, more loyal customers who know they’re investing in quality that lasts.

A full 18-inch strand gives us more flexibility when designing pearl necklace layouts, which allows us to offer a wider range of price points. Our goal is simple: we want every customer to have access to the “Queen of Pearls” without compromising on South Sea pearl necklace quality. Pure offers an array of South Sea pearl necklaces ranging from AA to AAAA quality, making it possible to find a beautiful, well-balanced strand for almost any budget.

From my professional perspective, I almost always recommend choosing a slightly smaller strand with higher overall quality rather than going bigger at the expense of luster. The same goes for shape. It’s easy to get fixated on “perfectly round,” but roundness alone doesn’t define beauty or value. What truly elevates South Sea pearl necklace quality is luster, and orient when visible.

Remember that luster - and orient whenever visible - makes or breaks these little guys as gemstones, so aim to up that “L” factor whenever possible.

That said, there’s no denying the WOW  Factor that a really large layout of White or Golden South Sea pearls exudes. The off-round / button-shape South Sea pearl necklace pictured just above crossed my desk in 2016 and was gone within a few weeks (because look at that Orient, it's to die for pretty)

Ultimately, what are the best quality South Sea pearls is up to you. Snagging a screaming deal like this depends on whether off-round and button-shaped pearls, or a few inclusions is a huge turn off for you, or if the luster and orient that is plain to see here overwhelms those other factors.

With Pure’s South Sea necklace collection, you’ll come across necklaces with grades that will look like "AA/AAA Quality" and/or "AAA/AAAA Quality" in their descriptions. These “intermediate” grades are given to pearl strands when the pearls almost-but-not-quite make it to a whole letter grade like AAA Quality.

Generally, what these intermediary grades mean is that the pearl’s surface quality (i.e. amount of inclusions) or shape is graded at a lower level like AA, but the pearl’s luster and shine pushes the layout to that higher grade.

It could also be the reverse in that the pearls’ surfaces are extremely clean, but the luster isn’t quite there. However, I usually grade strands like that with a lower grade anyways because what makes pearls beautiful as a gemstone?

That's right: Luster.

Let’s see how this plays out with real South Sea necklaces …

Check out the photo above showing a section of GRD-0817-PURE, an 18K Medium-Deep Golden South Sea Round Pearl Necklace which was given an intermediate AAA/AAAA Grade. Notice in particular:

• Bright, touchable Luster:  The high rate of light reflection from the pearl’s surfaces really brightens up the pearls, and gives these gorgeous gems a visual sense of depth, and helps the pearls appear to glow for the observer. The luster could be sharper and more defined around the edges of reflected light sources, so AAA Quality.
• Nicely saturated colors:  The strand featured is an 18K Medium-Deep Golden hue with pale silver, gold and subtle rose overtones. If the primary body color were deeper, say a 22K Golden hue, it would push the pearls into AAAA Grade territory.
• Well matched pearls:  The pearls are incredibly well matched for shape, size, luster, surface quality and overall tone. AAAA Quality level.
• Very light surface inclusions.  I count 5 very tiny blemishes in this center section, and the rest of the layout is really very clean. AAAA Quality, easily.

Surface blemishes, imperfections and natural growth characteristics that interrupt the smoothness of the pearl’s surfaces are what we call "inclusions" in the jewelry industry.

Nearly all South Sea pearls have natural surface features, and that’s completely normal. These pearls grow slowly inside living oysters, so a perfectly flawless surface is the exception, not the rule. Small marks or gentle variations are simply part of their natural character.

When pearl experts evaluate surface quality, they focus onwhat you can see at a normal viewing distance, not tiny details under a loupe. If a blemish isn’t noticeable when the pearls are worn, it usually has little impact on beauty or value. What matters most is the overall look and feel of the necklace.

Cleaner surfaces become especially important when pearls are matched for earrings or necklaces. The fewer visible blemishes there are, the easier it is to pair pearls that look balanced and harmonious together, which is why cleaner pearls elevate the quality and value of fine strands and classic stud earrings.

In this section, I’ll break down what is and is not an inclusion (it’s not always what you think): how these growth characteristics effect the pearl, and how they can affect value.  

Most White and Golden South Sea pearl blemishes are the color of the corresponding nacre (so, gold or white in color), so often these surface blemishes don’t stand out glaringly unless they’re very deep or there are a lot of them bunched together.

The pictures below are all of White and Golden South Sea pearl strands that are raw, unretouched photos (so no “glamourizing” has been done here).

Keep in mind that these are close-ups of inclusions on pearls for educational purposes … in other words, don’t get scared by the focusing on the spots.