Unlike diamonds, which have standardised grading from organisations like GIA, pearls lack a universal grading system. Different pearl dealers use various grading scales—A-AAA, A-AAAA, or descriptive terms like "gem quality." This inconsistency can make pearl shopping confusing. However, by understanding the factors that determine pearl quality, you can evaluate pearls yourself and make informed purchasing decisions regardless of the grading system used.
The Five Quality Factors
Pearl quality is determined by five key characteristics: lustre, surface quality, shape, size, and colour. Professional pearl graders and discerning buyers evaluate each factor, understanding that the interplay between them determines overall value and beauty.
💡 Important Context
Quality grading applies differently to different pearl types. A high-quality freshwater pearl won't match the lustre of a top-grade Akoya, but it represents excellent quality for its type. Always compare pearls within their category rather than across pearl types.
Lustre: The Most Important Factor
Lustre refers to the quality and intensity of light reflected from a pearl's surface and the deeper glow that seems to emanate from within. It's the characteristic that gives pearls their distinctive beauty and is universally considered the most important quality factor. A pearl with excellent lustre appears almost luminous, while poor lustre makes pearls look dull, chalky, or lifeless.
Evaluating Lustre
To assess lustre, examine pearls under diffused daylight or daylight-equivalent lighting. Avoid harsh direct light or spotlights, which can make even mediocre pearls appear more lustrous than they are. Hold the pearl at various angles and observe:
- Reflection clarity: High-lustre pearls reflect objects sharply, almost like a mirror. You should be able to see a relatively clear reflection of nearby objects or your own image. Lower-lustre pearls show blurred or indistinct reflections
- Light-dark contrast: Quality pearls show strong contrast between bright reflection areas and shadow areas. This depth gives pearls their dimensional appearance
- Inner glow: The finest pearls seem to glow from within, a phenomenon caused by light penetrating and reflecting off multiple nacre layers. This is distinct from surface reflection and indicates thick, high-quality nacre
Key Takeaway
Lustre is directly related to nacre quality. Pearls with thicker, more uniform nacre layers exhibit better lustre. When shopping online, request photos taken in natural lighting and ask about nacre thickness if the seller doesn't specify.
Surface Quality
No pearl is perfectly smooth—nature doesn't work that way. However, surface quality varies significantly, and understanding what to look for helps you make value judgments. Surface characteristics include blemishes (spots, bumps, or pits) and texture irregularities.
Types of Surface Imperfections
- Spots: Small areas of discolouration, either darker or lighter than the surrounding surface
- Pits: Small indentations in the surface
- Bumps: Raised areas on the pearl surface
- Wrinkles: Linear ridges or grooves
- Circles: Concentric rings around the pearl
- Cracks: Fractures in the nacre (these are serious flaws to avoid)
Evaluating Surface Quality
Examine pearls under magnification if possible, but also at normal viewing distance—minor imperfections visible under magnification may be invisible during wear. For earrings, minor blemishes on the back of the pearl (the side against your ear) are less concerning than those on the front-facing surface. High-quality pearls appear "clean" to the naked eye from normal conversation distance, even if close examination reveals minor characteristics.
Shape: Beyond Round
Perfectly round pearls command premium prices, but other shapes have their own beauty and value. Understanding shape categories helps you find pearls that match your aesthetic preferences and budget.
Shape Categories
- Round: Perfectly spherical, the rarest and most valuable shape for most pearl types. True rounds roll in a straight line when placed on a flat surface
- Near-round: Slightly off-round but appear spherical to the casual observer. These offer excellent value
- Oval/Button: Symmetrical but not spherical. Button shapes (flattened on one side) work particularly well for earrings
- Drop: Pear or teardrop shaped, popular for pendants and drop earrings
- Baroque: Irregularly shaped, each unique. High-quality baroques with excellent lustre have their own market and appeal
- Semi-baroque: Slightly irregular but with some symmetry
✅ Smart Shopping
For pearl earrings, the most important shape consideration is that both pearls match each other. A well-matched pair of near-round pearls often looks better than a mismatched pair of rounds. Always request photos showing both earrings side by side.
Size: Millimetres Matter
Pearl size is measured in millimetres, with larger pearls generally commanding higher prices (assuming other quality factors are equal). However, bigger isn't always better—the "right" size depends on personal preference, how you'll wear the pearls, and your budget.
Size Ranges by Pearl Type
- Freshwater: Commonly 5-12mm, with most popular sizes for earrings being 7-9mm
- Akoya: Typically 5-10mm, with 7-8mm being classic earring sizes
- Tahitian: Usually 8-16mm, with 9-11mm common for earrings
- South Sea: Generally 9-20mm, with 10-13mm popular for earrings
Size dramatically affects price—in some cases, moving up just 1mm can increase cost by 30-50% or more. If budget is a concern, consider whether a smaller pearl with excellent lustre might serve you better than a larger pearl with mediocre shine.
Colour: Body Colour and Overtones
Pearl colour has two components: body colour (the dominant overall colour) and overtone (translucent colours that appear over the body colour). Understanding this distinction helps you describe and evaluate pearls accurately.
Body Colours
Body colours range from white, cream, and silver to gold, pink, and black. There's no "best" body colour—it's entirely a matter of personal preference and what complements your skin tone and wardrobe. What matters for quality is that the colour is attractive, even, and consistent (for a pair of earrings).
Overtones
Overtones are the subtle secondary colours visible on pearl surfaces. White Akoya pearls, for example, might show rosé (pink), silver, or cream overtones. Tahitian pearls are famous for peacock overtones—a combination of green, purple, and gold. Strong, attractive overtones add value and visual interest to pearls.
Orient
The most prized pearls display "orient"—an iridescent rainbow effect that shimmers across the surface as the pearl moves. This phenomenon indicates exceptional nacre quality and significantly increases value.
Putting It All Together
When evaluating pearl earrings, consider all five factors in context:
- Prioritise lustre: A smaller pearl with exceptional lustre will look more beautiful than a larger dull one
- Check matching: Both earrings should match in size, shape, colour, and lustre
- Accept minor imperfections: Perfect pearls are rare and expensive; minor blemishes invisible during wear are acceptable
- Consider your priorities: Decide what matters most to you and allocate your budget accordingly
- Compare within types: Judge freshwater against freshwater, Akoya against Akoya
Remember that grade labels (A, AA, AAA) vary between sellers and have no universal standard. Trust your own evaluation of the quality factors more than grade labels, and don't hesitate to ask sellers specific questions about lustre, surface quality, nacre thickness, and origin.