Difference between revisions of "Pearl"

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pearls; natural pearls; Oriental pearls; perle (Dan., Fr.); Perle (Deut.); perla (Esp.); parel (Ned.); pérola (Port.); parel (Ned.)
 
pearls; natural pearls; Oriental pearls; perle (Dan., Fr.); Perle (Deut.); perla (Esp.); parel (Ned.); pérola (Port.); parel (Ned.)
  
== Other Properties ==
+
== Risks ==
  
Specific gravity for natural and Oriental pearls = 2.68-2.74; for cultured pearls = 2.70-2.79; and for freshwater pearls = 2.68
+
Easily damaged by acids. Deteriorates at low humidities. Easily scratchedMay be discolored by soap or skin oil.
 
+
== Physical and Chemical Properties ==
Texture: slightly rough 
 
 
 
Luster: pearly (iridescent)  
 
 
 
Color: white, pale yellow, pink, gray, brown, black
 
 
 
Most exhibit a sky -blue color fluorescence
 
 
 
{| class="wikitable"
 
|-
 
! scope="row"| Mohs Hardness
 
| 3 - 4
 
|-
 
! scope="row"| Density
 
| 2.68-2.4
 
|}
 
 
 
== Hazards and Safety ==
 
  
Easily damaged by acids. Deteriorates at low humidities. Easily scratchedMay be discolored by soap or skin oil.
+
* Specific gravity for natural and Oriental pearls = 2.68-2.74; for cultured pearls = 2.70-2.79; and for freshwater pearls = 2.68
 +
* Texture: slightly rough 
 +
* Luster: pearly (iridescent)  
 +
* Color: white, pale yellow, pink, gray, brown, black
 +
* Most exhibit a sky -blue color fluorescence
 +
* Mohs Hardness = 3 - 4
 +
* Density = 2.68-2.4
  
== Sources Checked for Data in Record ==
+
== Resources and Citations ==
  
 
* Oppi Untracht, ''Jewelry Concepts and Technology'', Doubleday & Co., Inc., New York City, 1985  Comment: specific gravity for Oriental pearls = 2.68-2.74, cultured = 2.70-2.79, freshwater pearls = 2.68; average hardness = Mohs 3-4; double refraction = 1.57
 
* Oppi Untracht, ''Jewelry Concepts and Technology'', Doubleday & Co., Inc., New York City, 1985  Comment: specific gravity for Oriental pearls = 2.68-2.74, cultured = 2.70-2.79, freshwater pearls = 2.68; average hardness = Mohs 3-4; double refraction = 1.57
Line 41: Line 29:
 
* Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982
 
* Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982
  
* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "pearl." Encyclopædia Britannica. 2004.  Encyclopædia Britannica Premium Service.  23 Dec. 2004 .
+
* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "pearl." Accessed 23 Dec. 2004 .
  
* Website address 1  Comment: http://www.geo.utexas.edu/courses/347k/redesign/gem_notes/pearl/pearl_main.htm -Gives density of natural pearls as 2.66-2.78 and cultured pearls as 2.72-2.78
+
* Website: http://www.geo.utexas.edu/courses/347k/redesign/gem_notes/pearl/pearl_main.htm -Gives density of natural pearls as 2.66-2.78 and cultured pearls as 2.72-2.78
  
* Wikipedia, the free encyclopedia, at http://www.wikipedia.com  Comment: http://en.wikipedia.org/wiki/Pearl (Accessed Nov. 9, 2005)
+
* Wikipedia: http://en.wikipedia.org/wiki/Pearl (Accessed Nov. 9, 2005)
  
 
* G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971
 
* G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971

Revision as of 13:07, 12 August 2020

Brooch with pearls
MFA# 1986.764

Description

A smooth, opaque, iridescent gem formed as a multilayered Nacre deposit around foreign matter embedded in the shells of mollusks. Nacre is composed of Aragonite crystals bound together with Conchiolin. The nacre is built up in thin, concentric layers that grow at rates of less than a millimeter per year. Large, natural pearls a rarity with the largest known pearl weighing 93 grams. The shape of the pearl depends on the shape of the embedded inclusion so most natural pearls are not spherical. Salt-water pearls, also called Oriental pearls, are found in the Persian Gulf, Gulf on Mannar, Myanmar, Tahiti, Borneo, New Guinea, Venezuela, and Australia. Since 1920, pearls have been cultured commercially.

See also Pearl, cultured, and Pearl, freshwater.

Synonyms and Related Terms

pearls; natural pearls; Oriental pearls; perle (Dan., Fr.); Perle (Deut.); perla (Esp.); parel (Ned.); pérola (Port.); parel (Ned.)

Risks

Easily damaged by acids. Deteriorates at low humidities. Easily scratched. May be discolored by soap or skin oil.

Physical and Chemical Properties

  • Specific gravity for natural and Oriental pearls = 2.68-2.74; for cultured pearls = 2.70-2.79; and for freshwater pearls = 2.68
  • Texture: slightly rough
  • Luster: pearly (iridescent)
  • Color: white, pale yellow, pink, gray, brown, black
  • Most exhibit a sky -blue color fluorescence
  • Mohs Hardness = 3 - 4
  • Density = 2.68-2.4

Resources and Citations

  • Oppi Untracht, Jewelry Concepts and Technology, Doubleday & Co., Inc., New York City, 1985 Comment: specific gravity for Oriental pearls = 2.68-2.74, cultured = 2.70-2.79, freshwater pearls = 2.68; average hardness = Mohs 3-4; double refraction = 1.57
  • Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971
  • Caring for your Collections, Arthur W Schulz (ed.), Harry N. Abrams, Inc. , New York, 1992

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