Care for Pearls | Pearls Care

Natural Pearls are very delicate gems and can be easily damaged by the surrounding conditions. It is extremely important to care for pearl jewelry. With proper care the gems will last for centuries.

1) When pearls are worn very often and close to the skin they get eroded or damaged with contact with even the mildest of acids given out by the skin. Hence the use of pearl jewelry very often in humid places is not advisable.

2) Pearl jewelry like pearl earrings, pearl rings etc should not be kept in cotton wool as it contains small amounts of acids that may damage the pearl in the long run.

3) String of pearls or pearl jewelry should not be kept in polythene bags as there isn?t enough moisture for the pearls in these bags, which will create a water loss and damage the outer surface of the pearls.

4) The best way of storing pearls would be to keep them well wrapped in white linen cloth or pure silk.

5) Cosmetics and perfumes must never come in contact with pearls as the acids and chemicals most certainly will damage them.

6) Restringing of pearls that are very often used is a very good idea as many a times the string may absorb the perfume of cosmetics used and in turn damage the pearl. The string used (if silk) by itself may wear out or may break. It is advisable to restring regularly used pearls once every six months.

7) The best way of stringing pears is to have a knot at the end of each pearl so that in case of breakage of the string only one pearl is lost.               

History and General Information on Natural Pearls 

Pearls are categorized as organic gem material and are amongst the oldest of precious gems. In history pearls have been very valuable, second only to the diamond. The first record of the use of pearls in history is the fishing of the famous orient Basra pearl around the year 300 B.C.

In India pearls are also called as ?moti?. It is one of the Navagraha stones (stones that represent the nine planets that have a cosmic influence on all earthlings) representing the Moon (Chandra) and is related to the mind.

Pearl is used to remove the evil effects of moon and it strengthens the mind and increases good sleep and cures insomnia. It is said to bestow the wearer with a good memory, cure uterine disorders, heart trouble, eye diseases, hysteria and pleurisy. It is also believed to increases sexual strength and makes conjugal life happy, removes melancholy and increases fortune. The gem must me mainly made in silver jewelry and worn in the little finger for therapeutically purposes.

Composition of Pearls

The chemical compostion of pearl is 82-86% calcium Carbonate, 10-14% conchiolin and 2-4% of water (CaCO3 and H2O). Its specific gravity is 2.65-2.85 and refractive index range is between 1.530-1.685. Pearl's hardness on Mohs scale is 3.5-4.

Types of Pearls

1. 

Natural Pearls

   - Freshwater Pearls
   - Saltwater Pearls

2. 

Cultured Pearls

   - Freshwater Pearls
   - Saltwater Pearls

Sorted according to colour, shape and size

Natural Pearls

The pearl producing oysters are very similar to the edible oysters. However the pearl producing oysters belong to a group of molluscs known as ?bivalve? (animal with double shell) and its scientific name being ?Lamellibranchia?. Almost any mollusc may produce the pearl, but only the pearl found in the bivalves have the fine luster and beauty to be used as gem material in jewelry.
The pearl may be formed as a blister pearl (half pearl) or round pearl (sphere shape). Both of these are formed by different methods inside the mollusks.

The blister pearl is found when any tiny stone or shell piece etc is trapped inside the oyster. This causes irritation to the animal. To ease out irritation the animal secretes nacre over the external body and cements it to the shell. The mollusc keeps layering the fixed particle with nacre and thus a pearl is formed. The pearl needs to be scraped off from the shell and is grounded to make the bottom flat. Sometimes it may also be covered with an appropriate piece of mother of pearl. These pearls are usually set in jewelry with close bottom setting to hide the flat bottom.

The highly priced natural spherical white pearls are not formed when any article or object is trapped in the mollusk but is formed when a minute parasite is trapped inside it. This parasite does not allow the oyster to cement them to the shell. So the mollusc creates a depression and traps the parasite on one side of the mantle. Then, by slowly encircling the parasite with the nacre it produces a hollow sac separating it from the main mantle of the oyster. This is called a pearl sac which remains trapped in the mollusc. The mollusc keeps secreting nacre and in turn keeps coating the pearl sac with one layer after another forming a highly valuable pearl.

Fresh Water Pearls

The pearls that are produced by molluscs that live in fresh waters are called fresh water pearls. These pearls have a subdued luster when compared to sea water pearls and are commercially less viable. The pearls formed in the Mississippi river (USA) are usually found with bizarre shapes (baroque) those similar to the shapes of wings, dog teeth, petals etc. These have been inspiration for many designers in the production of brooches and pendent with flower motifs in jewellery.  The famous Abernethy fresh-water pearl weighing 10.9 cts was found in Scotland?s river Tay in 1967. However the best known river pearls are found in the rivers of Europe and America.

Salt Water Pearls

The pearls that are produced by mollusc that live in salt water (sea) are called salt water pearls. Most of the pearls commercially used are salt water pearls. Along with the beautiful pearly luster of the pearls found in the sea water there is a pink to white variety of pearls which is commonly known as the conch pearl. These do not have the pearly luster and are produced by the giant conch (strombus gigas). Another variety of the salt water pearl is the clam pearl which is black in color and lacks pearly luster. These are found on the pacific coast of America.

Cultured Pearls

The limited availability of natural pearls has provoked man to experiment in stimulating the pearl from oyster to produce pearl with human help. The Chinese have been trying to culture pearls from the 13th century. In the 18th century a Swedish naturalist Carl V Linne experimented and tried to produce cultured pearls. However his attempts were not of commercial significance.

It was only around 1896 that a Japanese noodle vendor Kokichi Mikimoto started experimenting in this field. He successfully produced and marketed cultured pearls after 1913. His first successful experimentation produced the blister pearl which is now called as the mabe pearl and then he started commercially producing spherical pearl as well.

Cultured pearls are produced by inserting a spherical mother of pearl bead by forcibly opening the pearl oyster. Once the bead is correctly placed the oyster is closed and returned to the water where it remains for a year or two. It is noticed that the mother of pearl bead is coated with nacre by the oyster much faster than during the formation of natural pearl.

Physical Properties of Pearls

color

White or Cream is the color that comes to the mind when the word pearl is uttered. There are the rosée pearls that come in tints of pink, silver and white. Some of these may even have a yellowish tinge. The other fancy colors available in the market are yellow, bronze (champagne color pearl), gunmetal black, rose- pink, brown (chocolate color pearl), green and blue. The most popular and common color of the pearl is the rare ?natural Basra? which is creamy or white. The south sea pearls have a silvery white luster. Pearls from Venezuela are translucent white and Tahiti black are bronze to gunmetal color.

Shapes

The most common shape seen in the market is the round or spherical pearl, then there is the tear drop or pear shapes pearls. The button shaped pearls which are flat from the bottom and round from the top are also called as blister pearls or boutons. The irregular shaped very small pearls are called as baroques. There is another variety of pearls which is longish in shape are know as rice pearls in the market simply because they look like rice grains.

Price, Cost and Buying of Natural Pearls

Cultured pearls are relatively inexpensive as compared to its natural counterpart. Good quality 3 mm sized strand of cultured pearls should cost anywhere between $10 per gram to $25 per gram. The cost mainly depends upon the shape, luster and its surface finish. Irregular shaped pearls are very cheap and can be found for just $1 to $3 per gram. Natural pearls are very expensive and can cost anywhere from $40 per carat to $250 per carat depending on the size and quality.

Markets and Producers

Natural pearls are mainly found in Japan, Australia, Persian Gulf, USA, Tahiti and India (Gulf of Manaan). Fresh water pearls are found in Japan, USA and Chain.

The Major producers of cultured pearls are Japan and China, however countries like Australia, Myanmar and Thailand also produce pearls commercially. In India, Hyderabad is one of the largest processing, drilling and pearl jewelry manufacturing center.  

Treatments done on Pearls

Treatments like bleaching, irradiation, dyeing, skinning, oiling and staining are done on pearls. Bleaching, irradiation and dyeing is done to the gem to enhance the color or to get a desired color. Skinning of natural pearls may be done to give them a better luster. This is nothing but pealing off the outer layer of the gem, removing blemishes or damages and obtain a better quality pearl. The skinning process may damage the pearl and thus needs to be done by experienced artisans. Cracks on the surface of natural pearls may be filled by soaking the gem in warm olive oil. Again the warm oil may damage the pearls and there is a high risk of the color changing to low value brown.

Staining of natural as well as cultured pearls is carried out to get the rosée tint or a black pearl from other undesired dark pearls. The pearls may be soaked in sliver nitrate or hydrogen peroxide solution and then exposed to sun light or ultra-violet rays to get the desired color. This is not an acceptable trade practice and is not easily identifiable. 

Simulants of Pearls

Simulants of natural pearls are cultured pearls, wax filled paste (natural glass) beads, plastic beads, hematite and coral.

Interesting Trivia and other Pearl facts

The unit of measurement of cultured pearls in Japan is ?Momme?. Where 1 Momme = 3.75 gms or 18.75 carats. Where as in India pearls are weighed in unit called ?Chav?, where 1Chav= 1.259carats. Pearls are lucky for people born in the month of June and hence it is called as June Birthstone. Take proper care of your pearls and it will serve you for a life time to come.

Reference

1) Webster
2) Gemmology by Peter G.Read
3) Handbook of Gem Identification -   Richard  T.Liddicoat, jr
4) Gems and Crystals - From the American  Museum of Natural History - Anna S.Sofianides  and George E.Harlow.