Pearls have been a symbol of elegance
and class for centuries.
The Maharajas of India and European queens
adorned themselves with pearls, a
symbol of their prestige. At 2018's Catholic Church-inspired Met Gala, celebrities
walked the red carpet dripping in pearls.
Uma Thurman's dress had over 3,000
white pearls sewn to it,
while Rihanna's pope-inspired outfit
was encrusted in pearls. At the 2019 Grammys, Cardi B
was basically dressed like an
oyster.
The most expensive pearl ever sold
was Marie Antoinette's pendant. It
sold for $32 million in a 2018 auction.
But what is it that makes pearls so
expensive? Marie Antoinette's pearl was part
of a diamond-studded pendant,
and it has important historical
significance, which increased its value. But there are several other factors
that determine the value of a pearl.
Tom Moses: Assessing the value of a
pearl
is probably the most complex gem to
assess.
Narrator: That's Tom Moses.
He's a gemologist at the Gemological
Institute of America where he oversees diamond grading,
colored stone identification, and
pearl identification.
He says that part of the reason
the Marie Antoinette pearl is worth
so much is because it's a natural pearl,
which brings us to one quality that determines a pearl's value.
Natural versus cultured.
Natural pearls are hard to find.
They're rare, and this makes them
worth more money. But let's rewind for a second.
What is a natural pearl, and how are
they formed?
Natural pearls form when some kind
of irritant,
usually a small organism, makes its
way into the shell of a mollusk
like an oyster or a mussel. To protect itself from the invader,
the mollusk starts to coat the
debris with nacre, or mother-of-pearl, the same material
that lines the inner layer of its
shell. It continues doing this,
and the irritant grows into a shiny
pearl.
Cultured pearls are formed by the
same process,
but instead of the irritant entering
the shell accidentally,
it's put there intentionally by a
human. Pearl farmers insert a piece of mollusk tissue,
which is called donor tissue, into
the shell of the oyster where they want the pearl to grow.
This triggers the oyster's defense
response,
and it starts coating that piece of
tissue with nacre. The vast majority of pearls on the market
are cultured pearls. The Gemological
Institute of America
uses X-rays to tell if a pearl is
natural or cultured.
If you look closely at these two
images,
you can see the difference. Moses:
Think about the layers of an onion.
So a natural pearl would have all of
those concentric layers of growth from the very inside out.
Narrator: A cultured pearl, on the
other hand,
is like an orange, with a large
center
and a thinner layer of pearl growth
around that. The large center is the manmade irritant
placed in the shell to encourage
nacre formation.
Cultured pearls date all the way
back to around 500 AD in China. However, in 1893, the Japanese-born Kōkichi
Mikimoto streamlined the process
and eventually created perfectly
round pearls. Today, Mikimoto is widely considered
the grandfather of cultured pearls.
He used Akoya pearls, which are the
traditional white round pearls you're probably familiar with.
By the 1920s, cultured pearls became
more commercially available, which
made them more affordable and accessible to people who weren't royalty. But
just because you can grow a cultured pearl
doesn't mean it's an easy process. Pearl
farmers pry open the mollusk shell
just enough to implant the piece of
foreign tissue, then they put the oysters back in the water
and wait anywhere from six months to
two years for pearls to form, and not every pearl comes out the same,
which brings us to another quality
that can make one pearl worth more
than another.
Size. The larger the pearl, the more
valuable, just like any other gem.
Narrator: The size of the pearl
largely depends
on the size of the mollusk. Certain
oysters grow bigger than others
and can, therefore, make bigger pearls.
For example, Akoya pearls can only
grow to about 9 or 10 millimeters in diameter,
but South Sea pearls and black
Tahitian pearls
can reach a diameter of around 15 or
16 millimeters.
The larger size makes South Sea
pearls
and black pearls the most valuable
type of pearl. On Mikimoto's website,
this strand of South Sea cultured
pearls is selling for $32,000.
The other notable difference between
pearl types
is the color. Sometimes this goes
hand in hand with size
because the pearl's color is
determined mostly by the mollusk it comes from.
Tahitian black pearls are black
because the inside
of the Pinctada margaritifera oyster
is black,
but colors can vary slightly based
on the culturing process as well.
The main reason for the color
difference
is the species of the mollusk. Another
very interesting influence is when a pearl is cultured,
there is a donor tissue used from
another living mollusk,
and depending on the color of that
tissue, it will influence the color of the final cultured pearl.
Narrator: Take for example Akoya
pearls. These are all white pearls,
but the shade of white can still
vary.
Some strands might be slightly more
pink,
while others have more of a greenish
tint. Tom says that pinker pearls are typically preferred
over green hues.
Along with size and color, the shape
and surface of a pearl can have an impact on its value.
Typically the rounder and smoother,
the better. And finally, perhaps the hardest variable
to measure: luster.
Luster is essentially the way a
pearl reflects light.
The shinier the pearl, the better. But
it's hard to tell how shiny a pearl is
unless you have other pearls to
compare it to. That's why Tom and the rest of the Gemological Institute have a
collection of sample strands for comparison. That way they can look at how one
strand of pearls compares to another and see where it falls
on the luster scale. The quality of
a pearl's luster is influenced by the layers of nacre that coat the center. One
way to think of it is like the tiles of a roof.
Picture a roof with all the tiles
lined up so that everything fits together well.
If you translate that to a pearl, it
would result in a nice, high-luster pearl.
A dull, low-luster pearl would be
more like a roof with broken and fragmented tiles that don't line up. When you
take into consideration all of these factors, finding or creating
the perfect pearl is an art, and the
fact remains they're grown inside an animal, so it's impossible to have
complete control
over how and when they form, especially
in the wild. So if you ever bite down on something hard
while you're eating an oyster, take
a look at it before you chuck it.
It might be more than a piece of
sand.
