Pearl education
Pearl Quality
Two strands can sit side by side at the same size, the same color and the same stated grade, and one can be worth ten times the other. This page is about learning to see the difference.
Pearls are the only gem grown rather than mined, and that makes them harder to judge than a stone. There is no cut to assess and no universal report to fall back on. What you have instead is a set of things to look at, in a particular order, and a sense of what good looks like in each of them.
I have been buying pearls for close to thirty years, at auction in Japan, on farms in French Polynesia and China, and across a table in Hong Kong. The way I evaluate a parcel is not complicated and it is not secret. It is the seven things below, always in the same order, and the first one carries more weight than the rest combined.
~ Jeremy Shepherd, Founder and CEO of Pearl Paradise
Before anything else
Start with the type
Every judgment on this page depends on knowing what you are holding. Freshwater, akoya, Tahitian and South Sea are the four types of cultured pearl used in jewelry, each produced by a different mollusk in a different part of the world under very different conditions.
This matters because the standards are not transferable. A fine akoya throws a sharp, almost mirrored reflection. A fine South Sea does not, and is not supposed to. Judge a South Sea pearl against akoya luster and you will reject the better pearl.
The same is true of shape, of size, and of what counts as a clean surface. Every factor below has to be read against the type in front of you.
The whole method
What to look at, in order
Seven factors decide what a pearl is worth. They are not equal, and the order below is the order I use.
Luster
How sharply the pearl returns light. Everything else is secondary, and a pearl that fails here cannot be rescued by anything below.
Nacre
How much nacre is there and how well built it is. Thin nacre is the one flaw that gets worse with time rather than staying still.
Shape
Round is hardest to grow and holds the most value, but a fine drop or baroque beats a mediocre round pearl.
Color
Bodycolor and overtone together. Preference decides what you want. Rarity and whether the color is natural decide what it costs.
Surface
How clean the pearl is. Judge severity and position rather than counting marks, since a mark at the drill hole is not a mark on the face.
Size
Diameter in millimeters. Value climbs steeply with size, because every extra millimeter costs the farmer time and risk.
Matching
Only applies to strands, pairs and multi-pearl pieces, and on those it is often the difference between a good price and a serious one.
The numbering is the sequence I evaluate in, not a fixed hierarchy. Luster leads for every pearl type. Below that the weighting shifts, and on a strand matching can outrank almost everything.
Factor one
Luster
Luster is the quantity and quality of light returned from the surface and from just beneath it. It is the single most important thing about a pearl and it is the first thing I look at in any parcel.
The practical test is simple. Hold the pearl under a light and look for a reflection. On a fine pearl you will see the light source itself, with defined edges, and often the outline of the window or the room. As luster falls off, that reflection softens, then spreads, then disappears into a general glow.
What luster should look like depends entirely on the type. Fine akoya give a hard, almost mirrored reflection. South Sea give a broader, softer, satiny return, because the nacre is built from larger aragonite platelets. Tahitian sit between, with iridescence layered over. Freshwater are usually more diffuse, though the best of them show a metallic surface that rivals anything.
Weak luster is the one fault that cannot be worked around. A large, round, clean pearl with dull luster is a poor pearl.
Chalky or milky is the word to watch for. A pearl that looks white but flat, with no reflection to find, is showing you either thin nacre or poorly formed nacre. No amount of processing fixes it, and no discount makes it a good buy.
Factor two
Nacre
Nacre is the material the pearl is made of. It is deposited by the pearl sac, a structure that forms from the epithelial cells of a small piece of donor mantle tissue implanted during nucleation, and it is built from microscopic platelets of aragonite bound in an organic protein called conchiolin. It is the same substance that lines the inside of the shell, where it is called mother of pearl.
Nacre quality is assessed two ways, and most people only know about the first.
Thickness is how much nacre sits over the bead. It matters because thin nacre looks dull, wears through at the drill holes, and can eventually blister or peel. On a bead-nucleated pearl this is the one quality factor that gets worse over time rather than staying where it is.
Density matters as much as thickness, and it is the part that gets missed. Nacre laid down slowly in cold water packs tighter than nacre laid down fast in warm water. Two pearls can carry identical nacre thickness on an X-ray and look nothing alike, because one has compact, highly reflective nacre and the other does not. This is why a certificate quoting a thickness figure tells you less than it appears to.
Nacre thickness only applies to bead-nucleated pearls. Traditional freshwater pearls and keshi pearls are solid nacre all the way through, so there is no coating to measure and the question does not arise.
Factor three
Shape
A truly round pearl is rare. The mollusk is not trying to make one, and roundness is the outcome of a bead staying centered while nacre goes down evenly for years. The rounder the pearl, the more it is worth, all else equal.
Round is rarest of all in traditional freshwater pearls, which are grown without a bead. Pearls that look round to the unaided eye do exist, but genuinely round non-nucleated freshwater pearls are exceptionally uncommon. Bead nucleation is why round freshwater pearls became widely available at all.
The other shapes are not lesser. Drops and ovals are what fine earrings and pendants are built from, and a well matched pair of drops can be harder to assemble than a round pair. Baroques are valued for individuality, and circled Tahitian pearls, once treated as leftovers, are now used deliberately in contemporary jewelry.
The test that costs nothing is to roll a loose pearl across a flat surface. A round pearl runs straight. An out-of-round pearl wobbles, and you will see it immediately.
Shape is where the money is easiest to save. If a strand looks round on the neck and rolls with a slight wobble, you are buying near-round at a real discount, and nobody looking at you will know the difference.
Factor four
Color
Color has three parts, and separating them is most of the skill.
Bodycolor is the pearl's main color, the one you would name from across a room. Overtone is a secondary color sitting over it, most often rose, silver or green on white pearls. Orient is a shifting iridescence produced by exceptional nacre structure, and it is genuinely uncommon rather than a thing every fine pearl has.
Natural pearl colors run from white through cream, champagne, gold, pink, peach, lavender, silver, green, blue, aubergine and near black, depending on the type. What you prefer is entirely your business. What it is worth depends on how rare that color is within its own type, and on whether the color is natural.
That last point is where most of the money is made and lost. Deep golden South Sea, natural blue akoya and strongly colored natural freshwater all carry real premiums, and all three are imitated with treatment. Dye tends to gather in drill holes, pits and surface marks, so those are the places to look. Price that seems out of step with the stated rarity is the other signal.
Ask whether the color is natural, and expect a direct answer. Treatment is not a scandal and plenty of treated pearls are attractive, but an undisclosed treatment on a pearl priced as natural is a different matter entirely.
Factor five
Surface
Every pearl carries growth characteristics. They are the record of an animal building something over several years in open water, and a pearl with none at all does not exist. The question is never whether there are marks. It is how much they matter.
Four things decide that. How many marks there are, how large they are, how deep or disfiguring they are, and where they sit. A small pit beside the drill hole disappears the moment the pearl is strung. The same pit on the face of the pearl is the reason it costs less.
The marks themselves are pits, bumps, wrinkles, growth lines, scratches and dull patches. Of these, dull or chalky areas are the ones to take seriously, because they are usually telling you about the nacre underneath rather than about the surface.
Cleaner is worth more, but not at any price. Given a choice between a flawless pearl with soft luster and a lightly marked pearl with sharp luster, take the luster. It is the one everyone will notice.
Look at the piece the way it will be worn rather than under a loupe at arm's length. Marks that vanish at conversational distance are marks you should be happy to pay less for.
Factor six
Size
Pearls are measured by diameter in millimeters, and when everything else is equal the larger pearl is worth more. The relationship is not gentle. A single millimeter is a visible step on the neck and a substantial step in price, because every extra millimeter means more time in the water and more chances for the animal to die, reject the bead or produce something unsaleable.
What counts as large depends completely on the type. Akoya usually run in the six to eight millimeter range, and anything above ten millimeters is exceptional. South Sea pearls start where akoya finish and go far beyond. Freshwater now covers an enormous span, from seed pearls under a millimeter to bead-nucleated pearls well past fifteen.
Because of that, size on its own tells you very little. A ten millimeter akoya is a remarkable pearl. A ten millimeter South Sea is an ordinary one. The number only means something once you know what produced it.
Factor seven
Matching
Matching is the factor almost every guide leaves out, and on anything with more than one pearl in it, it is where the price actually separates.
A strand has to agree with itself in size, shape, bodycolor, overtone, luster, surface and nacre quality, all at once. On the finest strands the matching is mirrored, so the pearl third from the clasp on the left answers the pearl third from the clasp on the right. That is not an accident of sorting. It is a decision made pearl by pearl.
The reason it costs is inventory. Pearls come out of the water varying in every direction, so assembling forty that agree means owning several thousand that do not. For large South Sea pearls, a single fine strand can take years of accumulated production to build.
The same applies in miniature to a pair of earrings. Two pearls that match precisely are worth considerably more than twice one pearl, and a matched pair of drops can be harder to find than a matched pair of rounds.
Lay a strand flat and look down its length rather than at individual pearls. Poor matching shows up as a rhythm problem, a place where the eye catches, long before you can say which pearl is responsible.
Where grades come in
What a grade can and cannot tell you
Pearls have no equivalent of a diamond report. There is no international standard, no independent body whose word settles it, and no requirement that two companies mean the same thing by the same letters. A grade is a seller describing their own goods.
That does not make grading useless. Within one seller who applies it consistently, a grade is a reliable guide to where a piece sits in their range, and it is a fast way to compare two things on the same site. Across sellers it means very little, which is why an AAA strand from one company can sit beside an AA strand from another and lose.
So use grades the way they are actually good for. They tell you what a seller thinks they are offering. The seven factors above tell you what is in front of you.
How the systems work, what the letters mean, and how grading differs between the pearl types is a subject of its own, and we cover it separately.
