Pearl Quality
Pearl quality is evaluated using five criteria — all beginning with the letter S. Known as the 5×S system, it’s how we at Pearls.jp (Amit Trading, Tokyo) have graded pearls since 1969 — first as wholesalers supplying jewelers in 40+ countries, and today for customers buying directly from our Tokyo showroom and online store. Understanding the five S’s helps you make an informed choice — whether you are buying your first strand or adding to a collection.
Shine (Luster)
Luster is the single most important factor in determining a pearl’s value. It describes the pearl’s ability to absorb, break, and reflect light — creating depth and brilliance rather than a flat, chalky surface. High-luster pearls appear to glow from within, while low-luster pearls look dull and lifeless.
Luster is where we reject most pearls. Of the akoya lots offered to us in Tokyo each season, we accept roughly 30%. Luster, followed by surface quality, is the first and most common reason we pass. As a JPEA-member exporter, Amit Trading grades to the standards Japanese export houses have used for decades.
Luster is also the most reliable indicator of nacre quality and thickness. Thick, well-formed nacre layers produce sharp, bright reflections. Thin nacre produces a milky, diffused appearance.
How to check luster at home: Stand with your back to a light source and hold the pearl at arm’s length. In a high-luster pearl, you should be able to see your own reflection on the surface.
“Hold the strand and look for a sharp reflection. If the pearl shows good luster and richness of overtones, the rest is about balancing the other criteria.”
Size
Size is a significant price determinant. Pearl diameter is measured in millimeters and is the result of two variables: the size of the nucleus implanted during cultivation, and the thickness of the nacre that forms around it over time.
A large pearl is not automatically more valuable. A pearl with a large nucleus but thin nacre coating will have poor luster, and the surface may crack or discolor over time. Nacre thickness matters more than diameter alone.
This is the single most common mistake we see from first-time buyers at our Roppongi showroom: paying for millimeters instead of nacre. A 7.5mm akoya with thick nacre will outshine — and outlive — a 9mm pearl with a thin coat.
What to look for: Ask about nacre thickness, not just pearl size. A smaller pearl with thick nacre is a better long-term investment than a larger pearl with thin coating.
Shape
Perfectly round pearls are the rarest — fewer than 1% of all harvested pearls are truly spherical. Roundness is traditionally the most prized shape, and round pearls command the highest prices. To test roundness, roll a strand across a flat surface: a well-matched round strand will roll smoothly and evenly.
Beyond round, pearls occur in a variety of shapes: button, oval, drop, baroque, and keshi. Shape preference is personal — many collectors seek baroque and keshi pearls specifically for their organic, one-of-a-kind character.
Surface
Surface quality refers to the cleanliness of the pearl’s outer nacre — the presence or absence of pits, blemishes, bumps, and discolorations. High-quality pearls have smooth, uniform surfaces free of visible imperfections.
Some textures have specific industry names. “Orange skin” or “shark skin” describes a slightly rough, granular nacre texture visible under magnification. While minor blemishes are natural in all cultured pearls, large pits or spots in visible areas will lower the grade.
When we grade strands for wholesale clients, surface is checked pearl-by-pearl under fixed lighting — the same inspection every retail piece at Pearls.jp goes through before it’s listed.
Why nacre matters: Surface quality is directly linked to nacre formation. Thick, evenly deposited nacre layers create a smooth surface. Thin or uneven nacre leads to visible irregularities.
Shades (Color)
Pearl color has two components: body color and overtone. Body color is the dominant hue — white, pink, silver, cream, gold, or black. Overtone is the secondary translucent color that appears to float over the surface — common overtones include rosé, green, and blue.
The finest pearl colors appear to emanate from deep within the pearl rather than sitting on the surface. When evaluating a strand, color consistency matters — each pearl should match its neighbors in both body color and overtone.
Skin tone matters more than most guides admit: rosé overtones flatter cool complexions, cream and gold suit warm ones. Matching pearl to skin tone is most of what our Tokyo showroom consultations are for.
A note on grades: “AAA” is the industry’s shorthand for top grade — useful, but not standardized between sellers, so one shop’s AAA can be another’s AA+. What matters is who is grading, and to what standard. We grade to consistent Tokyo wholesale and export-house standards, and for the finest pearls, independent Hanadama certification (Pearl Science Laboratory, Tokyo) removes the guesswork — we can arrange it on premium akoya on request.
Choosing the right pearl for you.
Everyday Elegance
A strand you will wear daily should prioritize durability and versatile color.
- Key Shine (thick nacre = longevity)
- Key Surface (visible blemishes wear poorly)
- Consider Shape (near-round offers value)
Investment Grade
For pearls that hold or increase in value, every factor matters.
- Key Shine (excellent luster only)
- Key Shape (perfectly round)
- Key Size (larger = rarer)
- Key Surface (clean or near-clean)
The Perfect Gift
A gift should match the recipient’s style and skin tone above all else.
- Key Shades (match skin tone)
- Key Shine (the “glow” factor)
- Consider Size (occasion-appropriate)
These are the same criteria Amit Trading has used to grade pearls for brands, wholesalers and jewelers worldwide since 1969 — now applied to every piece sold at Pearls.jp.
There is no single “best pearl.” The right choice depends on your skin tone, your wardrobe, the occasion, and what draws your eye. Our specialists help match pearls to personal style — in person at the Tokyo showroom or through detailed consultation online.
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