Can calcite be used as pearl jewelry

Pearls and mother-of-pearl When shells produce jewelry

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Pearls can be round, oblong or pear-shaped, tiny or almost two centimeters in size, white, pink or almost black. They are always shimmering pieces of jewelry - the mussels produce for us in a very unromantic way.

Status: April 9th, 2021

They feel incredibly smooth and shine like small mirrors: pearls, the small, precious balls. More people worry about how much they cost and what they are used for than about where pearls actually come from: from shells, i.e. from living beings. Out of more than 10,000 shell species worldwide, only a few can produce pearls at all. And only a fraction of these are those that are also marketed as jewelry pearls.

Mussels - merciless mother-of-pearl producers

The genus is one of the best-known mussels that can produce mother-of-pearl and thus also pearls Pinctada. This pearl mussel is at home in salt water and secretes mother-of-pearl. "So if it lives and grows normally, it always produces mother-of-pearl," explains Gerhard Haszprunar, head of the Munich State Zoological Collection. Pearl mussels of the genus Hyriopsis live in fresh water, the genus Margaritifera even in rivers.

A shell that produces mother-of-pearl can also produce a pearl. The prerequisite for this: an injury to your coat tissue.

Sometimes a foreign body slips between the shell tissue of a mussel and its shell. "Then it too - like everything else - is encased in mother-of-pearl and that becomes a pearl," says Haszprunar. "The chemical composition is always the same: Calcite combined with organic intermediate layers," says Haszprunar. The shell actually does nothing but wall up intruders who have injured its interior. Even if with a beautiful layer that she covers them with over and over again.

Many meanings are ascribed to pearls

"Every pearl a tear"

Pearls are not only given positive meanings. For many, pearls symbolize tears.

For millennia, pearls have been considered treasures: in many different cultures they are symbols of femininity, beauty or wealth. They stand for perfection, in Buddhism for perfection and eternity. However, natural pearls are rarely large, exactly round, flawlessly white and evenly shimmering.
It is their shimmer that is the special feature of pearls. This peculiar luster is called a luster. It is caused by the refraction of light at the edges of the mother-of-pearl crystals. One reason why they used to be priceless and are still valuable and precious. If you ever discover one.

Pearls in the pearl farm: planting and harvesting

Almost all pearls are now cultivated. Several pearls can be produced in one shell at the same time.

For this reason, pearls have long been grown - or, better still, planted and harvested. There are two methods of vaccination: a transplant with or without a nucleus.

In the first method, a small mother-of-pearl ball is implanted in the mussel, along with a piece of mantle tissue from a donor mussel. The soft tissue is usually located just below the mussel shell and produces the shell from mother-of-pearl. The mussel reacts, forms the so-called pearl sack around the foreign body and covers it with mother-of-pearl. The implanted mother-of-pearl ball ensures that there is a high probability that the pearl becomes fully round - a cultured pearl with a core is created. With this pearl farming method, the death rate of the treated mussels is higher.

In the second method, which is mainly used with freshwater mussels, the bead is dispensed with and only a piece of foreign mantle tissue is implanted. This is enough to stimulate the mussel to produce a pearl.

In both methods, the recipient mussel encloses the foreign body layer by layer with mother-of-pearl. The pearl can be harvested after about two to three years. Or rather: the pearls. In some shells dozens of pearls are grown at the same time.
But the percentage of pearls that are actually harvested is very small: not even a third of all "vaccinated" mussels actually develop pearls. And mostly only a fraction of these can be used as jewelry.

Japanese patent for pearl cultivation

Until the end of the 19th century, there were only naturally occurring pearls. The fact that the noble balls are now available in all sizes and shades is thanks to a process that, among others, the Japanese Kokichi Mikimoto co-developed. In Asia, more than a thousand years ago, small Buddha figures were placed in pearl shells in order to have them covered with a layer of mother-of-pearl. However, the process fell into oblivion, was rediscovered at the end of the 19th century and continued. Mikimoto was particularly successful in this - and received a patent for his method in 1919. Pearls became affordable.

Pearls are not as hard as they look

They have remained sensitive: pearls can scratch and lose their shine. The knots between the pearls of a pearl necklace therefore not only prevent them from rolling over if they tear: The knots also keep the pearls at a distance - if they rub against each other, the mother-of-pearl wears off. But you should also be careful with creams, deodorants, perfumes or hairspray - they attack the surface of the pearl.

Pearls before the ... chickens

Caring for and protecting pearls

It is also better to proceed gently when cleaning pearls: "If you want to clean pearls, lukewarm water is enough, maybe a shot of alcohol," recommends Jonas J├╝ckstock, restorer from Munich. "But to restore the pearlescent luster that has been lost over the years is difficult and sometimes even impossible." In older recommendations, the restorer found a very special tip: "It was advised to feed the pearls to chickens. The pearls should pass through the chicken's body and then be in a better shine. I've never tried that ... I actually stop the lukewarm water, "says J├╝ckstock.

Mussels are sensitive beings: they need oxygen, clean water and a certain water temperature. Around 99 percent of all pearls now come from cultured stocks. The natural mussel populations of the seas are severely impaired by the increasing pollution.

There are also hardly any river pearl mussels left. Because pearls also arise in some rivers in Bavaria. But the population of these native pearl mussels fell sharply. For this reason, for example, the Bund Naturschutz (BN) operated a breeding station for the freshwater pearl mussel from 2018 to 2020, until funding for the project came to an end.

Pearl powder for cosmetics

But not all of the farmed mussels make it onto the market. Lower quality pearls are either beautified, for example bleached with hydrogen peroxide - or immediately pulverized, then they end up in the cosmetics industry. If you don't wear pearls around your neck, you might wear them on your face: as a skin cream. Pearl powder was used in Asian cosmetics thousands of years ago. Today it is mainly used to give cosmetic products a touch of luxury.

  • The pearl mussel - last minute rescue? Schwaben & Altbayern, April 19th, 2020 at 5:45 p.m., BR television
  • Rescue for the pearl mussel. Frankenschau, 09/22/2019 at 5:45 p.m., BR television
  • Bavaria's pearl mussel. Between Spessart and Karwendel, May 25, 2019 at 5:45 p.m., BR television
  • Mother-of-pearl and pearl - jewelry of shells. May 24, 2018, 3:05 p.m., radioWissen in the afternoon, Bavaria 2.