Pearl

Big Photo

Pacific Ocean
22.54 carats
© Palagems

Pearl is a mixture of mineral and organic material formed with the soft living tissue of a shelled mollusk. Chemically pearls are made of calcium carbonate (mainly aragonite or a mixture of aragonite and calcite).

Pearls have been used for adornment for 6,000 years. Pearls do not require any processing because they show full gloss and attractive lustre in their natural state.

Pearls are used as gemstones, but are not regarded as true minerals due to their organic origin.

Pearl Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
 
 
 
 
 

Pearl Gemstones by Size

This table shows distribution of Pearl gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:3.5 cts
Heaviest:30.75 cts
Average:16.06 cts
Total photos:24
Do you have a larger Pearl? Why not upload a photo?
3.50ct to 6.23ct6.23ct to 8.95ct8.95ct to 11.68ct11.68ct to 14.40ct14.40ct to 17.13ct17.13ct to 19.85ct19.85ct to 22.58ct22.58ct to 25.30ct25.30ct to 28.03ct28.03ct to 30.75ct
Pearl Treatments
White pearls are routinely bleached to lighten the dark spots of conchiolin (undetectable). Dyed mostly golden, pink, gray, silvery-black, chocolate colors: standard tests limited. Acetone or diluted acids may reveal the dye. Dyed black: LW - generally inert. Dyed yellow and golden (and/or heated): may show small spots of color concentration. LW - light blue to mottled pink orangy-yellow (even body color with uneven fluorescence is suspicious). Irradiated to create a grayish-black body color (gamma rays), bluish and bronze hue. Color division between whitish nacre and dark nucleus may sometimes be seen in the drill hole or using a strong transmitted light - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 8
Pearl Simulants
Fish-scale pearl is a glass or enamel coated with essence, which is produced from scales of certain fish. Other imitations are: parts of sea snails (antilles pearls); mussels (takara pearls from Japan); teeth (of the sea cow-dugong pearl); the mabé pearl (consists of a thin mother-of-pearl layer and some artificial part - clay or resin bead); plastic products. - Gemstones of the world, Walter Schumann, 2001, p 239
Physical Properties of Pearl
Mohs Hardness2.5 to 4.5
Walter Schumann, Gemstones of the world (2001)
More from other references
Specific Gravity2.60 to 2.85
Walter Schumann, Gemstones of the world (2001)
More from other references
Cleavage QualityNone
Walter Schumann, Gemstones of the world (2001)
FractureUneven
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Pearl
Refractive Index1.52 to 1.66
Walter Schumann, Gemstones of the world (2001) Black: 1.53 - 1.69More from other references
Birefringence0.156
Walter Schumann, Gemstones of the world (2001)
More from other references
PleochroismAbsent
Walter Schumann, Gemstones of the world (2001)
DispersionNone
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)White, pink, silver-, cream-, golden-coloured, green, blue, black.
Walter Schumann, Gemstones of the world (2001)
More from other references
TransparencyTranslucent,Opaque
Walter Schumann, Gemstones of the world (2001)
More from other references
Fluorescence & other light emissions
Fluorescence (Long-Wave UV)White pearls: common light blue to light yellow; Yellow and golden pearls: yellow-green, greenish brown to dark brown; Black: commonly pink to (orangy)-red
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Crystallography of Pearl
Crystal SystemOrthorhombic
Walter Schumann, Gemstones of the world (2001)
Geological Environment
Where found:Formed by saltwater oysters, some fresh-water mussels and more rarely by other shellfish.
Walter Schumann, Gemstones of the world (2001)
Further Information
Mineral information:Pearl information at mindat.org
Significant Gem Localities
Australia
 
  • Northern Territory
French Polynesia
 
  • Tuamotu-Gambier (Tuamotu and Gambier Islands)
Copyright © Jolyon & Katya Ralph 1993-2017. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.