The Types Of Pearls Reading Passage
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The Types Of Pearls Reading Passage
Paragraph A
Throughout history, pearls have held a unique presence within the wealthy and powerful. For instance, pearls were the favourite gem of the wealthy during the Roman Empire. This gift from the sea had been brought back from the Orient by the Roman conquests. Roman women wore pearls to bed so they could be reminded of their wealth immediately upon waking up. Before jewellers learned to cut gems, the pearl was of greater value than the diamond. In the Orient and Persia Empire, pearls were ground into powders to cure anything from heart disease to epilepsy, with possible aphrodisiac uses as well. Pearls were once considered an exclusive privilege for royalty. A law in 1612 drawn up by the Duke of Saxony prohibited the wearing of pearls by the nobility, professors, doctors or their wives in an effort to further distinguish royal appearance. American Indians also used freshwater pearls from the Mississippi River as decorations and jewellery.
Paragraph B
There are essentially three types of pearls: natural, cultured and imitation. A natural pearl (often called an Oriental pearl) forms when an irritant, such as a piece of sand, works its way into a particular species of oyster, mussel, or clam. As a defence mechanism, the mollusc secretes a fluid to coat the irritant. The layer upon layer of this coating is deposited on the irritant until a lustrous pearl is formed.
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The only difference between natural pearls and cultured pearls is that the irritant is a surgically implanted bead or piece of shell called Mother of Pearl. Often, these shells are ground oyster shells that are worth significant amounts of money in their own right as irritant catalysts for quality pearls. The resulting core is, therefore, much larger than in a natural pearl. Yet, as long as there are enough layers of nacre (the secreted fluid covering the irritant) to result in a beautiful, gem-quality pearl, the size of the nucleus is of no consequence to beauty or durability.
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Pearls can come from either salt or freshwater sources. Typically, saltwater pearls tend to be of higher quality, although there are several types of freshwater pearls that are considered high in quality as well. Freshwater pearls tend to be very irregular in shape, with a puffed rice appearance, the most prevalent. Nevertheless, it is each individual pearl’s merits that determine value more than the source of the pearl. Saltwater pearl oysters are usually cultivated in protected lagoons or volcanic atolls. However, most freshwater cultured pearls sold today come from China. Cultured pearls are the response of the shell to a tissue implant. A tiny piece of mantle tissue from a donor shell is transplanted into a recipient shell. This graft will form a pearl sac, and the tissue will precipitate calcium carbonate into this pocket. There are a number of options for producing cultured pearls: use freshwater or seawater shells, transplant the graft into the mantle or the gonad, add a spherical bead or do it non-beaded. The majority of saltwater cultured pearls are grown with beads.
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Regardless of the method used to acquire a pearl, the process usually takes several years. Mussels must reach a mature age, which can take up to 3 years, and then be implanted or naturally receive an irritant. Once the irritant is in place, it can take up to another 3 years for the pearl to reach its full size. Often, the irritant may be rejected, the pearl will terrifically misshapen, or the oyster may simply die from disease or countless other complications. By the end of a 5 to 10-year cycle, only 50% of the oysters will have survived. Of the pearls produced, only approximately 5% are of substantial quality for top jewellery makers. From the outset, a pearl farmer can figure out how much to spend, over $100 for every oyster that is farmed, of which many will produce nothing or die.
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Imitation pearls are a different story altogether. In most cases, a glass bead is dipped into a solution made from fish scales. This coating is thin and may eventually wear off. One can usually tell an imitation by biting on it. Fake pearls glide across your teeth, while the layers of nacre on real pearls feel gritty. The Island of Mallorca (in Spain) is known for its imitation pearl industry. Quality natural pearls are very rare jewels. The actual value of a natural pearl is determined in the same way as it would be for other “precious” gems. The valuation factors include size, shape, colour, quality of surface, orientation, and lustre. In general, cultured pearls are less valuable than natural pearls, whereas imitation pearls almost have no value. One way that jewellers can determine whether a pearl is cultured or natural is to have a gem lab perform an x-ray of the pearl. If the X-ray reveals a nucleus, the pearl is likely a bead-nucleated saltwater pearl. If no nucleus is present, but irregular and small dark inner spots indicating a cavity are visible, combined with concentric rings of organic substance, the pearl is likely cultured freshwater. Cultured freshwater pearls can often be confused with natural pearls, which present as homogeneous pictures that continuously darken toward the surface of the pearl. Natural pearls will often show larger cavities where organic matter has dried out and decomposed. Although imitation pearls look the part, they do not have the same weight or smoothness as real pearls, and their lustre will also dim greatly. Among cultured pearls, Akoya pearls from Japan are some of the most lustrous. A good quality necklace of 40 Akoya pearls measuring 7 mm in diameter sells for about $1,500, while a super-high-quality strand sells for about $4,500. Size, on the other hand, has to do with the age of the oyster that created the pearl (the more mature oysters produce larger pearls) and the location in which the pearl was cultured. The South Sea waters of Australia tend to produce larger pearls, probably because the water along the coastline is supplied with rich nutrients from the ocean floor. Also, the type of mussel common to the area seems to possess a predilection for producing comparatively large pearls.
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Historically, the world’s best pearls came from the Persian Gulf, especially around what is now Bahrain. The pearls of the Persian Gulf were naturally created and collected by breath-hold divers. The secret to the special lustre of Gulf pearls probably derived from the unique mixture of sweet and saltwater around the island. Unfortunately, the natural pearl industry of the Persian Gulf ended abruptly in the early 1930s with the discovery of large deposits of oil. Those who once dove for pearls sought prosperity in the economic boom ushered in by the oil industry. The water pollution resulting from spilt oil and indiscriminate overfishing of oysters essentially ruined the once pristine pearl-producing waters of the Gulf. Today, pearl diving is practised only as a hobby. Still, Bahrain remains one of the foremost trading centres for high-quality pearls. In fact, cultured pearls are banned from the Bahrain pearl market in an effort to preserve the location’s heritage. Nowadays, the largest stock of natural pearls probably resides in India. Ironically, much of India’s stock of natural pearls came originally from Bahrain. Unlike Bahrain, which has essentially lost its pearl resource, traditional pearl fishing is still practised on a small scale in India.
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