Pearl education
Natural blue pearls
Blue akoya are among the most sought-after akoya in the world, and for most of the last century almost nobody outside Japan had seen one.
The color is entirely natural and it comes from inside the pearl. Nothing is added, nothing is dyed, and no two are quite alike.
I found a basket of them at a farm in southern China in 2007 and had no idea what I was looking at. This page is what I have learned since: how the color forms, how to tell a fine one from a poor one, and how a color hardly anyone knew about became one people ask for by name.
~ Jeremy Shepherd, Founder and CEO of Pearl Paradise
The short answer
Where the blue comes from
Natural blue akoya get their color from something that went wrong during nucleation. Organic material is deposited onto the bead before the pearl sac begins laying down nacre. That material is dark, closer to brown than blue, and once nacre covers it the pearl reads blue.
Two things decide what color you end up with. How much of that material there is and how dark it is, and how much nacre ends up over the top of it. A pale silver pearl and a deep steel blue one can differ on either count.
It is worth sitting with that for a moment, because it explains almost everything about these pearls. The color is not pigment in the nacre the way a Tahitian's color is. It is a dark layer underneath, seen through the nacre above it, which is why the blue shifts as the pearl turns and why the finest of them show so much orient.
It also explains why they are irregular. Whatever disrupts the graft tends to disrupt the shape as well, so blue akoya are usually baroque rather than round.
And it explains why they cannot be produced to order. A farmer cannot decide to grow blue akoya. They turn up, in small numbers, in a harvest grown for something else.
Most importantly, it gives you a test. The nacre is doing two jobs at once: carrying the color and covering what produces it. Too little of it and the brown underneath starts coming through. That is most of how we select them.
The distinction that matters
Three ways a pearl ends up blue
One is an accident inside the shell. One is a decision made before the pearl starts growing. One is done to the pearl after it comes out.
Natural
During growth, by accident
Blue akoya
Organic material deposited on the bead before nacre begins. Dark underneath, blue once the nacre covers it.
Usually baroque, because whatever disrupted the graft disrupted the shape too. Never uniform across a strand.
Tell: variation. Color shifts pearl to pearl and across a single pearl, and the surface carries orient.
Treated
Before growth, by design
Dark-nucleus freshwater
A bead-nucleated freshwater pearl grown over a bead that was dark to begin with. Recent, and still working its way into the market.
Cobalt-60 will not work on freshwater, because it would darken the nacre along with the bead. So the bead starts dark instead.
Tell: shape. These are round, formed cleanly around the bead with nothing interfering, where natural blue akoya are almost always baroque.
Treated
After harvest
Irradiated akoya
Cobalt-60 irradiation. The radiation interacts with manganese in the freshwater-mussel bead and darkens the bead itself.
The nacre is unchanged. The darkened core shows through it, imitating the natural effect.
Tell: uniformity, and a color that sits flat rather than moving.
None of this makes treated blue pearls bad. They are attractive and inexpensive, and sold honestly there is nothing wrong with them. But natural and treated blue are priced very differently, and the difference is worth being able to see.
Xuwen, April 2007
A basket I did not recognize
I had a stake in an akoya farm in Xuwen, in southern China, and in April 2007 I was there for the first harvest. It was a short-lived experiment. A typhoon destroyed the farm in the second year and that was the end of it.
What I remember from the first harvest is a basket. Thousands of pearls, separated out from the rest, in a color I had never seen on an akoya.
I was travelling with Doug Fiske, who was writing GIA's pearl course at the time, and Valeria Powers from GIA. I had been taking them around freshwater farms and had brought them out to Xuwen. None of us had seen akoya like these.
I asked my partner to drill them and send them to me. Back home I went through about ten kilograms of loose pearls to find enough matching pieces for a single strand.
On 2 May I posted a photograph of that strand on Pearl-Guide, without saying what it was, and asked people to guess. The thread is still there, nine pages of it.
They guessed Sea of Cortez. They guessed light Tahitian. They guessed freshwater. One member got there and then talked herself out of it: what about baroque akoyas in a weird color? Oh but they are too big to be akoyas. I give up.
That is the part I still find telling. Someone reached the right answer and rejected it, because the pearls did not fit what an akoya was understood to be.
GIA had the same reaction, and asked to photograph the strand. It appeared in Gems & Gemology that summer, in the Gem News section, as natural-color silver-blue baroque akoya from China. The same strand that had just stumped a forum full of people who look at pearls for a living.
What happened next
A color people started asking for
Natural color akoya were not new. Old strands exist, and anyone who had spent time in Japan had seen them. What they were not was available. They were held back rather than offered, and very few people outside the trade knew they existed at all.
That changed over the following few years. By 2009 blue and baroque akoya were turning up at Tucson. By 2011 GIA's pearl course treated naturally bluish baroque akoya as an established variety and illustrated Chinese examples.
What I think happened is straightforward. Buyers had spent a decade looking at heavily dyed freshwater pearls and were ready for something that had not been colored at all. Once people had seen an untreated pearl in an unusual color, the appetite for the alternative dropped.
We still buy them. They surface unpredictably, in small numbers, and we take what we can when it appears.
The other blue
Blue Tahitian
Blue occurs in Tahitian pearls as well, and there it is the rarest color of all. Not the most wanted, which is a different thing and worth keeping separate. Peacock outsells blue comfortably and probably always will.
But rarity and popularity are two different measurements, and on rarity blue wins. A strand of genuinely blue Tahitian pearls, matched, is something most people in the trade will not handle in a given year.
The mechanism is not the same as in akoya. Tahitian color comes from the shell, carried into the pearl by the donor tissue, so a blue Tahitian is blue the way a green one is green. It is a color the animal produces rather than an accident of the graft.
If you are buying
Telling a fine one from a poor one
There are a great many poor blue baroque akoya in the world. They are cheap, they are widely available, and at a glance across a screen they photograph much like the good ones. The difference is nacre thickness, and there is a way to see it.
Beige is the warning
Remember what is producing the color. A dark, roughly brown organic layer sits on the bead, and the blue you see is that layer through the nacre laid over it.
So when a blue baroque starts showing beige or brown, you are not looking at a color variation. You are looking at the layer underneath, coming through because the nacre above it is too thin to cover it properly.
That is the test. Fine blue akoya read blue, silver, steel, sometimes green or violet as they turn. A pearl that reads muddy brown is a pearl with thin nacre, and thin nacre on an akoya is the fault that gets worse rather than staying still.
It is the first thing I look for in a parcel, and it sorts a lot very quickly.
Then everything else
Luster, as with any pearl. The blue draws you in and it is not what decides whether the strand is any good.
Variation. Natural blue akoya are never consistent, because the process producing the color is an accident repeated at slightly different scales in every shell. A strand where every pearl matches almost exactly is worth asking about.
Orient. The finest show a prismatic play across the surface that is uncommon in akoya generally, and it is good evidence of nacre depth. It is the positive version of the beige test: brown means too little, orient means plenty.
And expect baroque. Round natural blue akoya do occur, and the finest of them, round and clean, are known in the trade as madama. They are extraordinarily scarce. A round strand offered as natural blue at an ordinary price deserves a question.
Availability
We buy them when they surface
There is no production schedule for these. They come out of harvests grown for something else, they are sorted out by hand, and the quantity in any given year is whatever the year happened to produce. We keep people in Japan watching for them and we buy what appears.
Which means the collection changes and there is rarely much of it. If you are looking for a particular size or a particular depth of color, it is worth telling us so we can watch for it.
