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GIA Graduate Gemologist - GEM 220 - Colored Stones > Assignment 16 - Pearl Formation, Types, and Market > Flashcards

Assignment 16 - Pearl Formation, Types, and Market Flashcards

1
Q

An organic gem that forms in
the body of a mollusk.

A

Pearl

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2
Q

A pearl that forms without human assistance.

A

Natural pearl

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3
Q

A pearl formed as the result of human intervention in the formation process.

A

Cultured pearl

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4
Q

The organ that lines the mollusk’s shell, encloses its soft body, and contains the cells that form pearl sacs and secrete nacre.

A

Mantle

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5
Q

The natural substance produced by pearl-bearing mollusks to make pearls.

A

Nacre

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6
Q

A crystallized form of calcium carbonate found in nacre.

A

Aragonite

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7
Q

The organic “glue” in nacre that holds aragonite platelets together.

A

Conchiolin

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8
Q

What causes a mollusk to form a pearl?

A

Natural pearl formation starts when a foreign object gets inside a pearl-bearing mollusk’s shell and irritates its soft tissue

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9
Q

Why did the natural pearl market decline?

A

Pearl culturing, plastic buttons, and oil drilling all contributed to the decline of the natural pearl industry.

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10
Q

How do natural pearls fit into today’s marketplace?

A

Today, there’s little financial
incentive to harvest mollusks for natural pearls. A shell diver might search hundreds or even thousands of mollusks without finding a single natural pearl. And of those found, few would be gem quality.

In the US, shell divers find natural pearls in the freshwater mussel shells they collect for use in making bead nuclei.

Some natural pearls found in the marketplace are from old inventories or estate sales.

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11
Q

The nacreous layer inside a pearl-bearing mollusk’s shell.

A

Mother-of-pearl

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12
Q

Pearl with a non-concentric structure of aragonite crystals resulting in different luster and appearance from nacreous
pearls.

A

Non-nacreous pearl

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13
Q

Optical phenomenon created in
some non-nacreous pearls when intersecting groups of crystals interact with light.

A

Flame structure

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14
Q

A cultured pearl grown around a nucleus implanted under the mantle tissue inside a mollusk’s shell.

A

Cultured blister pearl

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15
Q

A bead used as the core of a cultured pearl, usually made from a freshwater mussel shell.

A

Bead nucleus

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16
Q

How did the cultured pearl industry develop?

A

Modern pearl culturing began about 1890, when several Japanese researchers and a few Australians independently pursued blister pearl culturing. One of those original researchers was Kokichi Mikimoto.

Because he was the only one who went on to great commercial success in pearl culturing and marketing, he gets most of the attention from historians.

During World War II, the Japanese cultured pearl industry virtually shut down. Mikimoto was the first to revive the industry in the post-war period.

In the mid- to late-1940s, American soldiers purchased a great number of cultured pearl necklaces to take home to their wives and sweethearts. That was a significant step in the popularization of cultured pearls in the US.

17
Q

What are the basics of pearl culturing?

A

Pearl culturing is an adaptation of the natural pearl formation process:

A saltwater cultured whole pearl grows from a mantle-tissue piece and a bead nucleus implanted in a host mollusk’s gonad.

Most freshwater cultured whole pearls are grown from mantle-tissue pieces implanted in a host mollusk’s mantle.

18
Q

What are the four major types of cultured pearls?

A

The four major types of cultured whole pearls are akoya, South Sea, Tahitian, and freshwater.

19
Q

A small square of mantle tissue cut from a donor mollusk and implanted in a host mollusk with or without a bead.

A

Mantle-tissue piece

20
Q

The reproductive organ that
produces eggs in females and sperm in males.

A

Gonad

21
Q

Tissue that encloses an implanted bead nucleus and mantle tissue piece, or the piece alone, and secretes nacre to form a cultured pearl.

A

Pearl sac

22
Q

What are the features of Akoya pearls?

A
  • 2 - 11mm diameter (small)
  • uniform size (good for strands)
23
Q

Common name for the Pinctada fucata oyster and the natural or cultured pearls it produces.

A

Akoya

24
Q

A simple necklace typically
composed of pearls; also, pearls very close to the same size strung without a clasp for whole-sale marketing.

A

Strand

25
Q

A necklace featuring pearls that are very nearly the same size.

A

Uniform strand

26
Q

A necklace with the largest pearl in the center and progressively smaller pearls approaching the clasp.

A

Graduated strand

27
Q

A facility where biologists breed pearl-bearing mollusks in tanks under controlled conditions

A

Hatchery

28
Q

Describes mollusks bred in laboratory tanks and grown
in protected areas rather than
collected as adults in the wild.

A

Hatchery-bred

29
Q

What are the features of South Sea cultured pearls?

A
  • 8 - 18mm
  • soft, satiny luster
  • Indonesia, Australia, Philippines
30
Q

A three-step freshwater
cultivation process involving a series of distinct growth periods.

A

Coin-bead/spherical-bead (CBSB)
production

31
Q

Product that results when a
pearl-bearing mollusk is returned to the water after the first harvest.

A

Second-generation cultured pearl

32
Q

The oyster used to grow Tahitian cultured pearls is the

A. Pinctada fucata.

B. Pinctada maxima.

C. Hyriopsis cumingii.

D. Pinctada margaritifera.

A

D. Pinctada margaritifera.

33
Q

Chinese freshwater cultured pearls first appeared on the international market around

A. 1960.

B. 1970.

C. 1980.

D. 1990.

A

B. 1970.

34
Q

A number of similar cultured pearl strands bundled together.

A

Hank

35
Q

A company that prepares cultured pearls for the market.

A

Processor

36
Q

South Sea cultured pearls are produced principally in Australia, Indonesia, Myanmar, and

A. India.

B. Tahiti.

C. Japan.

D. the Philippines.

A

D. the Philippines.

37
Q

Very small natural pearls produced by both saltwater and freshwater mollusks.

A

Seed pearls

38
Q

Accidental byproducts of the pearl culturing process.

A

Keshi

39
Q

By what date had Kokichi Mikimoto begun culturing whole pearls?

A. 1908

B. 1920

C. 1932

D. 1954

A

A. 1908

GIA Graduate Gemologist - GEM 220 - Colored Stones (27 decks)

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