Difference between revisions of "Gemstone"

From CAMEO
Jump to navigation Jump to search
 
(8 intermediate revisions by the same user not shown)
Line 1: Line 1:
−
[[File:gempebbles.jpg|thumb|Polished gemstones]]
+
[[File:Precious-gemstone-names.gif|thumb|Cut Gemstones<br>Credit:  Alvonzo Zone]]
 
== Description ==
 
== Description ==
−
 
+
[[File:gempebbles.jpg|thumb|Polished gemstones<br>Credit: Adrian Pingstone]]
−
An ornamental, often valuable, mineral used for decoration in jewelry, small objects and clothing. Gemstones are normally transparent, crystalline stones such as [[diamond|diamonds]], [[ruby|rubies]], [[sapphire|sapphires]], [[emerald|emeralds]], [[topaz]], and [[garnet|garnets]]. Non-transparent gems include [[cat's eye]] chrysoberyl. Non-stone materials that have sometimes been used as gems are [[ivory]], [[amber]], [[jet]], and [[coral]]. Gems are found in alluvial deposits and dug from veins. Major mining locations include Sri Lanka, southeast Asia, South Africa, Australia, Russia, Brazil and Colombia. Gemstones are characterized based on their color, clarity, cut and weight. Stones of exceptional size, beauty or rarity are highly valued. Techniques for cutting and polishing gemstones were developed in India in the 14th century.
+
An ornamental, often valuable, mineral used for decoration in jewelry, small objects and clothing. Gems are found in alluvial deposits and dug from veins. Major mining locations include Sri Lanka, southeast Asia, South Africa, Australia, Russia, Brazil and Colombia. Gemstones are characterized based on their color, clarity, cut and weight. Stones of exceptional size, beauty or rarity are highly valued. Techniques for cutting and polishing gemstones were developed in India in the 14th century.  Gemstones can usually be classified into three types:
 +
* Transparent crystalline stones; usually cut: [[amethyst]], [[aquamarine]], [[citrine]], [[emerald]], [[diamond|Diamonds]], [[garnet|Garnets]], [[peridot]], [[quartz]], [[ruby|Rubies]], [[sapphire|Sapphires]], [[spinel]], [[tanzanite]], [[topaz]], [[tourmaline]], and [[zircon]].  
 +
* Non-transparent minerals, usually polished:  [[agate]], [[carnelian]], [[cat's eye]], [[chrysoberyl]], [[chrysocolla]], [[jasper]], [[lapis lazuli]], and [[turquoise]]
 +
* Non-stone materials: [[ivory]], [[amber]], [[jet]], and [[coral]]
  
 
[[File:Diamondcutkes.jpg|thumb|Gemstone facet cuts]]
 
[[File:Diamondcutkes.jpg|thumb|Gemstone facet cuts]]
−
 
+
Properties of Common Gemstones
 +
{| class="wikitable"
 +
|-
 +
! colspan="2" | Mineral
 +
! colspan="2" | Gem
 +
! colspan="2" | Color
 +
! colspan="2" | Mohs hardness
 +
! colspan="2" | Specific gravity
 +
! colspan="2" | Refractive index
 +
! colspan="2" | Crystal system
 +
! colspan="2" | Other
 +
! colspan="2" | Fluorescence
 +
! colspan="2" | Dispersion
 +
! colspan="2" | Inclusions
 +
|-
 +
| rowspan="5" colspan="2" | beryl
 +
| colspan="2" | aquamarine
 +
| colspan="2" | sky blue
 +
| rowspan="5" colspan="2" | 7.5-8.0
 +
| rowspan="3" colspan="2" | 2.68-2.71
 +
| rowspan="3" colspan="2" | epsilon =  1.570-1.580<br />    omega  =  1.574-1.586
 +
| rowspan="5" colspan="2" | hexagonal  crystal system; conchoidal fracture
 +
| rowspan="5" colspan="2" | transparent;  weakly pleochroic
 +
| rowspan="5" colspan="2" | none to  weak; synthetic stones may appear opaque and dull red in longwave UV
 +
| rowspan="5" colspan="2" | <br /> <br /> <br /> <br />
 +
| rowspan="5" colspan="2" | Aquamarines  are often flawless;  Other contain many  inclusions such as mica, pyrite and calcite
 +
|-
 +
| colspan="2" | goshenite
 +
| colspan="2" | colorless
 +
|-
 +
| colspan="2" | heliodor
 +
| colspan="2" | yellow
 +
|-
 +
| colspan="2" | emerald
 +
| colspan="2" | green
 +
| colspan="2" | 2.68-2.78
 +
| colspan="2" | epsilon = 1.571-1.581<br />    omega  =  1.577-1.588
 +
|-
 +
| colspan="2" | morganite
 +
| colspan="2" | pink
 +
| colspan="2" | 2.66-2.83
 +
| colspan="2" | epsilon = 1.580-1.590<br />    omega  =  1.589-1.601
 +
|-
 +
| colspan="2" | chrysoberyl
 +
| colspan="2" | alexandrite
 +
| colspan="2" | green in daylight, red in  incandescent light
 +
| colspan="2" | 8.5
 +
| colspan="2" | 3.5-3.8
 +
| colspan="2" | alpha  = 1.745<br />    beta  =  1.748<br />    gamma  =  1.754
 +
| colspan="2" | orthorhombic, flattened  crystals, often twinned
 +
| colspan="2" | transparent; chrysoberyl  cat's-eye is<br />    chatoyant
 +
| colspan="2" | strongly pleochroic
 +
| colspan="2" | d = 0.015
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | cristobalite
 +
| colspan="2" | opal
 +
| colspan="2" | milky white to colorless;;  variable pale shades
 +
| colspan="2" | 5.5-6.5
 +
| colspan="2" | 1.98-2.25
 +
| colspan="2" | 1.435-1.455
 +
| colspan="2" | tetragonal  submicrocrystalline aggregates; irregular concretions; glass-<br />    like fracture
 +
| colspan="2" | opaque; contains some water  causing the physical properties to<br />    vary
 +
| colspan="2" | may fluoresce white or pale  green; may phosphoresce
 +
| colspan="2" |
 +
| colspan="2" | possible
 +
|-
 +
| rowspan="3" colspan="2" | corundum
 +
| colspan="2" | sapphire
 +
| colspan="2" | blue
 +
| rowspan="3" colspan="2" | 9.0
 +
| rowspan="3" colspan="2" | 4.0
 +
| rowspan="3" colspan="2" | epsilon =  1.757-1.768<br />    omega  =  1.765-1.776
 +
| rowspan="3" colspan="2" | hexagonal;  conchoidal fracture
 +
| rowspan="3" colspan="2" | transparent;  marked dichroism
 +
| rowspan="3" colspan="2" | orange to  red; heat treated stones may fluoresce green
 +
| rowspan="3" colspan="2" | d = 0.018
 +
| rowspan="3" colspan="2" | many  including minerals (rutile), fluids, angular<br />    banding
 +
|-
 +
| colspan="2" | ruby
 +
| colspan="2" | red
 +
|-
 +
| colspan="2" | padmaradschah
 +
| colspan="2" | orange
 +
|-
 +
| colspan="2" | diamond
 +
| colspan="2" | diamond
 +
| colspan="2" | variable (colorless, yellow,  blue)
 +
| colspan="2" | 10.0
 +
| colspan="2" | 3.52
 +
| colspan="2" | 2.4175
 +
| colspan="2" | isometric flattened  octahedrons; dodecahedrons
 +
| colspan="2" | transparent; perfect  cleavage in four directions
 +
| colspan="2" | may fluoresce pale colors in  longwave UV; may<br />    phosphoresce
 +
| colspan="2" | d = 0.044
 +
| colspan="2" | trigonal on surface;  numerous inclusions
 +
|-
 +
| rowspan="3" colspan="2" | potash feldspar
 +
| colspan="2" | orthoclase
 +
| colspan="2" | pale yellow to flesh red
 +
| rowspan="3" colspan="2" | 6.0-6.5
 +
| rowspan="3" colspan="2" | 2.6
 +
| rowspan="3" colspan="2" | alpha =  1.518<br />    beta  =  1.522<br />    gamma = 1.522
 +
| colspan="2" | monoclinic crystals
 +
| colspan="2" | two perfect cleavages at  right angles
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | moonstone
 +
| colspan="2" | colorless, white to  yellowish
 +
| colspan="2" | nodules or masses
 +
| colspan="2" | blue opalecsence
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | amazonite
 +
| colspan="2" | yellow green to blue green
 +
| colspan="2" | triclinic, large crystals
 +
| colspan="2" | variety of microcline
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| rowspan="2" colspan="2" | plagioclase feldspar
 +
| colspan="2" | sunstone (aventurine)
 +
| colspan="2" | colorless to pale pink
 +
| rowspan="2" colspan="2" | 6.0-6.5
 +
| rowspan="2" colspan="2" | 2.6-2.7
 +
| rowspan="2" colspan="2" | alpha =  1.527-1.577<br />    beta=1.531-1.585<br />    gamma = 1.538-1.590
 +
| rowspan="2" colspan="2" | triclinic  prismatic crystals; two perfect cleavages at right angles
 +
| rowspan="2" colspan="2" | transparent  to opaque; iridescent;
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" | inclusions give spangled  appearance
 +
|-
 +
| colspan="2" | labradorite
 +
| colspan="2" | grayish shades
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | fluorite
 +
| colspan="2" | fluorite
 +
| colspan="2" | lavender to green
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" | 1.434
 +
| colspan="2" | conchoidal fracture
 +
| colspan="2" | transparent
 +
| colspan="2" | strong
 +
| colspan="2" |
 +
| colspan="2" | color zoning
 +
|-
 +
| rowspan="5" colspan="2" | garnet
 +
| colspan="2" | almandine (carbuncle)
 +
| colspan="2" | deep red with a trace of  purple
 +
| colspan="2" | 7.0-7.5
 +
| colspan="2" | 4.3
 +
| colspan="2" | 1.79-1.83
 +
| rowspan="5" colspan="2" | isometric  euhedral crystals, with dodecahedrons and trapezodrons most common;  conchoidal fracture
 +
| rowspan="5" colspan="2" | light  colored varieties are transparent; no birefringence, no pleochroism
 +
| colspan="2" | none
 +
| colspan="2" | d = 0.024
 +
| rowspan="5" colspan="2" | needles;  single and multiphase prisms
 +
|-
 +
| colspan="2" | andradite  (Uralian emerald)
 +
| colspan="2" | deep emerald-green
 +
| colspan="2" | 6.5-7.0
 +
| colspan="2" | 3.9
 +
| colspan="2" | 1.887
 +
| colspan="2" | none
 +
| colspan="2" | d = 0.057
 +
|-
 +
| colspan="2" | grossularite  (hessonite)
 +
| colspan="2" | yellow-brown to orange, red,  or green
 +
| colspan="2" | 7.0-7.5
 +
| colspan="2" | 3.6
 +
| colspan="2" | 1.734-1.740
 +
| colspan="2" | pale orange in long UV;  yellow in short UV
 +
| colspan="2" | d = 0.028
 +
|-
 +
| colspan="2" | pyrope
 +
| colspan="2" | dark blood red
 +
| colspan="2" | 7.0-7.5
 +
| colspan="2" | 3.78
 +
| colspan="2" | 1.714-1.742
 +
| colspan="2" | none
 +
| colspan="2" | d = 0.027
 +
|-
 +
| colspan="2" | spessartine
 +
| colspan="2" | yellow-orange to brown- red
 +
| colspan="2" | 7.0-7.5
 +
| colspan="2" | 4.15
 +
| colspan="2" | 1.800-1.810
 +
| colspan="2" | none
 +
| colspan="2" | d = 0.027
 +
|-
 +
| rowspan="2" colspan="2" | jade
 +
| colspan="2" | jadeite (Imperial jade)
 +
| colspan="2" | green but may be white,  black, red, brown, yellow, blue or mauve
 +
| colspan="2" | 6.0
 +
| colspan="2" | 3.33-3.34
 +
| colspan="2" | alpha = 1.640-1.658<br />    beta=1.645-1.663<br />    gamma = 1.652-1.673
 +
| colspan="2" | monoclinic compact or  fibrous masses; granular to splintery fracture
 +
| colspan="2" | translucent to opaque;  greasy luster
 +
| colspan="2" | may have pale white color in  long UV light
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | nephrite
 +
| colspan="2" | deep spinach green to  near-white
 +
| colspan="2" | 6.0-6.5
 +
| colspan="2" | 2.96-3.02
 +
| colspan="2" | alpha = 1.600-1.672<br />    beta=1.614-1.686<br />    gamma = 1.627-1.693
 +
| colspan="2" | monoclinic compact masses;  conchoidal to granular fracture
 +
| colspan="2" | translucent to opaque;  greasy or waxy appearance
 +
| colspan="2" | none
 +
| colspan="2" |
 +
| colspan="2" | some  dark inclusions
 +
|-
 +
| colspan="2" | lazurite
 +
| colspan="2" | lapis lazuli
 +
| colspan="2" | azure blue with flecks of  white and gold
 +
| colspan="2" | 5.0-5.5
 +
| colspan="2" | 2.7-2.9
 +
| colspan="2" | 1.50-1.67
 +
| colspan="2" | isometric with compact  masses; opaque
 +
| colspan="2" | decomposed by hydrochloric  acid
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | olivine
 +
| colspan="2" | peridot; chrysolite
 +
| colspan="2" | yellow green; dark bottle  green; olive green
 +
| colspan="2" | 6.5-7.0
 +
| colspan="2" | 3.3-3.4
 +
| colspan="2" | alpha = 1.635-1.671<br />    beta  =  1.652-1.698<br />    gamma = 1.671-1.707
 +
| colspan="2" | orthorhombic system with  massive or granular forms; fracture=uneven to conchoidal
 +
| colspan="2" | transparent
 +
| colspan="2" |
 +
| colspan="2" | d = 0.020
 +
| colspan="2" |
 +
|-
 +
| rowspan="8" colspan="2" | quartz
 +
| colspan="2" | amethyst
 +
| colspan="2" | purple
 +
| rowspan="8" colspan="2" | 7.0
 +
| rowspan="8" colspan="2" | 2.65
 +
| rowspan="8" colspan="2" | epsilon =  1.553<br />    omega  =  1.544
 +
| rowspan="5" colspan="2" | conchoidal  fracture
 +
| rowspan="5" colspan="2" | transparent;  heat treatment may bleach stones
 +
| colspan="2" |
 +
| colspan="2" | d = 0.013
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | cairngorm  (smoky quartz)
 +
| colspan="2" | smoky brown
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | citrine
 +
| colspan="2" | yellow
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | rock crystal
 +
| colspan="2" | colorless
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | rose quartz
 +
| colspan="2" | pink
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | agate (moss  agate, mocha stone)
 +
| colspan="2" | variable
 +
| rowspan="3" colspan="2" | compact  masses; nodules
 +
| rowspan="3" colspan="2" | translucent  to opaque
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | chalcedony  (onyx, carnelian, sardonyx, chrysoprase, bloodstone,<br />    heliotrope)
 +
| colspan="2" | variable
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | jasper
 +
| colspan="2" | variable
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| colspan="2" | spinel
 +
| colspan="2" | Balas ruby;
 +
| colspan="2" | typically red; also  variable: yellow (rubicelle), violet (almandine), pleonast (blue, black),  gahnite (blue-green)
 +
| colspan="2" | 8
 +
| colspan="2" | 3.6
 +
| colspan="2" | 1.715-1.725
 +
| colspan="2" | isometric octahedral  crystals; rounded grains; conchoidal fracture
 +
| colspan="2" | transparent
 +
| colspan="2" | natural fluoresces red in  longwave UV; synthetic may show colors in<br />    shortwave UV
 +
| colspan="2" | d = 0.020
 +
| colspan="2" | fingerprint pattern  inclusions
 +
|-
 +
| colspan="2" | topaz
 +
| colspan="2" | topaz, hyacinth
 +
| colspan="2" | yellow, green, blue, violet  or red
 +
| colspan="2" | 8
 +
| colspan="2" | 3.4-3.6
 +
| colspan="2" | alpha = 1.606-1.629<br />    beta = .609-1.631<br />    gamma = 1.616-1.638
 +
| colspan="2" | orthorhombic prismatic  crystals; perfect cleavage in one direction
 +
| colspan="2" | transparent; highly  pleochroic; turns soft red when heated
 +
| colspan="2" | may fluoresce yellow in  longwave UV
 +
| colspan="2" | d = 0.014
 +
| colspan="2" | single and multiphase
 +
|-
 +
| rowspan="6" colspan="2" | tourmaline
 +
| colspan="2" | achroite
 +
| colspan="2" | colorless or green
 +
| rowspan="6" colspan="2" | 7-7.5
 +
| rowspan="6" colspan="2" | 2.9-3.2
 +
| rowspan="6" colspan="2" | epsilon =  1.610-1.650<br />    omega  =  1.635-1.675
 +
| rowspan="6" colspan="2" | hexagonal  prismatic crystals, often rounded or oval; conchoidal fracture
 +
| rowspan="6" colspan="2" | transparent;  pleochroic
 +
| rowspan="6" colspan="2" | none to weak
 +
| rowspan="6" colspan="2" | d = 0.016
 +
| rowspan="6" colspan="2" | gas and  liquid pockets with color zoning
 +
|-
 +
| colspan="2" | dravite
 +
| colspan="2" | brown
 +
|-
 +
| colspan="2" | indicolite
 +
| colspan="2" | blue
 +
|-
 +
| colspan="2" | rubellite
 +
| colspan="2" | pink
 +
|-
 +
| colspan="2" | schorl
 +
| colspan="2" | black
 +
|-
 +
| colspan="2" | siberite
 +
| colspan="2" | violet
 +
|-
 +
| colspan="2" | turquoise
 +
| colspan="2" | turquoise
 +
| colspan="2" | blue to greenish-blue
 +
| colspan="2" | 5.0-6.0
 +
| colspan="2" | 2.6-2.9
 +
| colspan="2" | alpha = 1.61<br />    beta  =  1.62<br />    gamma = 1.65
 +
| colspan="2" | cryptocrystalline to fine  granular; fracture=conchoidal
 +
| colspan="2" | opaque; color fades in  sunlight
 +
| colspan="2" |
 +
| colspan="2" |
 +
| colspan="2" |
 +
|-
 +
| rowspan="4" colspan="2" | zircon
 +
| colspan="2" | jargon
 +
| colspan="2" | variable
 +
| rowspan="4" colspan="2" | 6.0-7.5
 +
| rowspan="4" colspan="2" | 4.6-4.7
 +
| rowspan="4" colspan="2" | epsilon =  1.968-2.015<br />    omega<br />    = 1.923-1.960
 +
| rowspan="4" colspan="2" | tetragonal  system with square prismatic crystals; fracture=uneven
 +
| rowspan="4" colspan="2" | transparent;  pleochroic
 +
| rowspan="4" colspan="2" | some show  dull yellow color; some may phosphoresce
 +
| rowspan="4" colspan="2" | d = 0.048
 +
| rowspan="4" colspan="2" | rutile  crystals; single and multiphase
 +
|-
 +
| colspan="2" | Matura diamond
 +
| colspan="2" | colorless
 +
|-
 +
| colspan="2" | hyacinth
 +
| colspan="2" | yellow orange
 +
|-
 +
| colspan="2" | jacinth
 +
| colspan="2" | red brown
 +
|}
 
== Synonyms and Related Terms ==
 
== Synonyms and Related Terms ==
  
 
gemstones; gem; gem; ædelsten (Dan.); Schmucksteine (Deut.); gema (Esp.); gemme (Fr.); edelsteen (Ned.); gema (Port.); Ädelsten (Sven.)
 
gemstones; gem; gem; ædelsten (Dan.); Schmucksteine (Deut.); gema (Esp.); gemme (Fr.); edelsteen (Ned.); gema (Port.); Ädelsten (Sven.)
  
−
== Comparisons ==
+
== For easy print or to download ==
  
 
[[media:download_file_414.pdf|Properties of Common Gemstones]]
 
[[media:download_file_414.pdf|Properties of Common Gemstones]]
Line 16: Line 404:
 
[[media:download_file_413.pdf|Natural and Simulated Diamonds]]
 
[[media:download_file_413.pdf|Natural and Simulated Diamonds]]
  
−
== Sources Checked for Data in Record ==
+
==Resources and Citations==
−
 
 
−
* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "gemstone." Encyclopædia Britannica. 10 Nov. 2004 .
 
  
 +
* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "gemstone." Accessed 10 Nov. 2004 .
 
* C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979
 
* C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979
−
 
 
* ''The Dictionary of Art'', Grove's Dictionaries Inc., New York, 1996  Comment: Gems: cutting. by Ken Scaratt
 
* ''The Dictionary of Art'', Grove's Dictionaries Inc., New York, 1996  Comment: Gems: cutting. by Ken Scaratt
−
 
+
* Wikipedia: http://en.wikipedia.org/wiki/Gemstone (Accessed Nov. 2, 2005)
−
* Wikipedia, the free encyclopedia, at http://www.wikipedia.com  Comment: http://en.wikipedia.org/wiki/Gemstone (Accessed Nov. 2, 2005)
 
  
  
  
 
[[Category:Materials database]]
 
[[Category:Materials database]]

Latest revision as of 12:40, 13 October 2024

Cut Gemstones
Credit: Alvonzo Zone

Description

Polished gemstones
Credit: Adrian Pingstone

An ornamental, often valuable, mineral used for decoration in jewelry, small objects and clothing. Gems are found in alluvial deposits and dug from veins. Major mining locations include Sri Lanka, southeast Asia, South Africa, Australia, Russia, Brazil and Colombia. Gemstones are characterized based on their color, clarity, cut and weight. Stones of exceptional size, beauty or rarity are highly valued. Techniques for cutting and polishing gemstones were developed in India in the 14th century. Gemstones can usually be classified into three types:

Gemstone facet cuts

Properties of Common Gemstones

Mineral Gem Color Mohs hardness Specific gravity Refractive index Crystal system Other Fluorescence Dispersion Inclusions
beryl aquamarine sky blue 7.5-8.0 2.68-2.71 epsilon = 1.570-1.580
omega = 1.574-1.586 		hexagonal crystal system; conchoidal fracture transparent; weakly pleochroic none to weak; synthetic stones may appear opaque and dull red in longwave UV



Aquamarines are often flawless; Other contain many inclusions such as mica, pyrite and calcite
goshenite colorless
heliodor yellow
emerald green 2.68-2.78 epsilon = 1.571-1.581
omega = 1.577-1.588
morganite pink 2.66-2.83 epsilon = 1.580-1.590
omega = 1.589-1.601
chrysoberyl alexandrite green in daylight, red in incandescent light 8.5 3.5-3.8 alpha = 1.745
beta = 1.748
gamma = 1.754 		orthorhombic, flattened crystals, often twinned transparent; chrysoberyl cat's-eye is
chatoyant 		strongly pleochroic d = 0.015
cristobalite opal milky white to colorless;; variable pale shades 5.5-6.5 1.98-2.25 1.435-1.455 tetragonal submicrocrystalline aggregates; irregular concretions; glass-
like fracture 		opaque; contains some water causing the physical properties to
vary 		may fluoresce white or pale green; may phosphoresce possible
corundum sapphire blue 9.0 4.0 epsilon = 1.757-1.768
omega = 1.765-1.776 		hexagonal; conchoidal fracture transparent; marked dichroism orange to red; heat treated stones may fluoresce green d = 0.018 many including minerals (rutile), fluids, angular
banding
ruby red
padmaradschah orange
diamond diamond variable (colorless, yellow, blue) 10.0 3.52 2.4175 isometric flattened octahedrons; dodecahedrons transparent; perfect cleavage in four directions may fluoresce pale colors in longwave UV; may
phosphoresce 		d = 0.044 trigonal on surface; numerous inclusions
potash feldspar orthoclase pale yellow to flesh red 6.0-6.5 2.6 alpha = 1.518
beta = 1.522
gamma = 1.522 		monoclinic crystals two perfect cleavages at right angles
moonstone colorless, white to yellowish nodules or masses blue opalecsence
amazonite yellow green to blue green triclinic, large crystals variety of microcline
plagioclase feldspar sunstone (aventurine) colorless to pale pink 6.0-6.5 2.6-2.7 alpha = 1.527-1.577
beta=1.531-1.585
gamma = 1.538-1.590 		triclinic prismatic crystals; two perfect cleavages at right angles transparent to opaque; iridescent; inclusions give spangled appearance
labradorite grayish shades
fluorite fluorite lavender to green 1.434 conchoidal fracture transparent strong color zoning
garnet almandine (carbuncle) deep red with a trace of purple 7.0-7.5 4.3 1.79-1.83 isometric euhedral crystals, with dodecahedrons and trapezodrons most common; conchoidal fracture light colored varieties are transparent; no birefringence, no pleochroism none d = 0.024 needles; single and multiphase prisms
andradite (Uralian emerald) deep emerald-green 6.5-7.0 3.9 1.887 none d = 0.057
grossularite (hessonite) yellow-brown to orange, red, or green 7.0-7.5 3.6 1.734-1.740 pale orange in long UV; yellow in short UV d = 0.028
pyrope dark blood red 7.0-7.5 3.78 1.714-1.742 none d = 0.027
spessartine yellow-orange to brown- red 7.0-7.5 4.15 1.800-1.810 none d = 0.027
jade jadeite (Imperial jade) green but may be white, black, red, brown, yellow, blue or mauve 6.0 3.33-3.34 alpha = 1.640-1.658
beta=1.645-1.663
gamma = 1.652-1.673 		monoclinic compact or fibrous masses; granular to splintery fracture translucent to opaque; greasy luster may have pale white color in long UV light
nephrite deep spinach green to near-white 6.0-6.5 2.96-3.02 alpha = 1.600-1.672
beta=1.614-1.686
gamma = 1.627-1.693 		monoclinic compact masses; conchoidal to granular fracture translucent to opaque; greasy or waxy appearance none some dark inclusions
lazurite lapis lazuli azure blue with flecks of white and gold 5.0-5.5 2.7-2.9 1.50-1.67 isometric with compact masses; opaque decomposed by hydrochloric acid
olivine peridot; chrysolite yellow green; dark bottle green; olive green 6.5-7.0 3.3-3.4 alpha = 1.635-1.671
beta = 1.652-1.698
gamma = 1.671-1.707 		orthorhombic system with massive or granular forms; fracture=uneven to conchoidal transparent d = 0.020
quartz amethyst purple 7.0 2.65 epsilon = 1.553
omega = 1.544 		conchoidal fracture transparent; heat treatment may bleach stones d = 0.013
cairngorm (smoky quartz) smoky brown
citrine yellow
rock crystal colorless
rose quartz pink
agate (moss agate, mocha stone) variable compact masses; nodules translucent to opaque
chalcedony (onyx, carnelian, sardonyx, chrysoprase, bloodstone,
heliotrope) 		variable
jasper variable
spinel Balas ruby; typically red; also variable: yellow (rubicelle), violet (almandine), pleonast (blue, black), gahnite (blue-green) 8 3.6 1.715-1.725 isometric octahedral crystals; rounded grains; conchoidal fracture transparent natural fluoresces red in longwave UV; synthetic may show colors in
shortwave UV 		d = 0.020 fingerprint pattern inclusions
topaz topaz, hyacinth yellow, green, blue, violet or red 8 3.4-3.6 alpha = 1.606-1.629
beta = .609-1.631
gamma = 1.616-1.638 		orthorhombic prismatic crystals; perfect cleavage in one direction transparent; highly pleochroic; turns soft red when heated may fluoresce yellow in longwave UV d = 0.014 single and multiphase
tourmaline achroite colorless or green 7-7.5 2.9-3.2 epsilon = 1.610-1.650
omega = 1.635-1.675 		hexagonal prismatic crystals, often rounded or oval; conchoidal fracture transparent; pleochroic none to weak d = 0.016 gas and liquid pockets with color zoning
dravite brown
indicolite blue
rubellite pink
schorl black
siberite violet
turquoise turquoise blue to greenish-blue 5.0-6.0 2.6-2.9 alpha = 1.61
beta = 1.62
gamma = 1.65 		cryptocrystalline to fine granular; fracture=conchoidal opaque; color fades in sunlight
zircon jargon variable 6.0-7.5 4.6-4.7 epsilon = 1.968-2.015
omega
= 1.923-1.960 		tetragonal system with square prismatic crystals; fracture=uneven transparent; pleochroic some show dull yellow color; some may phosphoresce d = 0.048 rutile crystals; single and multiphase
Matura diamond colorless
hyacinth yellow orange
jacinth red brown

Synonyms and Related Terms

gemstones; gem; gem; ædelsten (Dan.); Schmucksteine (Deut.); gema (Esp.); gemme (Fr.); edelsteen (Ned.); gema (Port.); Ädelsten (Sven.)

For easy print or to download

Properties of Common Gemstones

Natural and Simulated Diamonds

Resources and Citations

  • Encyclopedia Britannica, http://www.britannica.com Comment: "gemstone." Accessed 10 Nov. 2004 .
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • The Dictionary of Art, Grove's Dictionaries Inc., New York, 1996 Comment: Gems: cutting. by Ken Scaratt
  • Wikipedia: http://en.wikipedia.org/wiki/Gemstone (Accessed Nov. 2, 2005)

Retrieved from "https://cameo.mfa.org/index.php?title=Gemstone&oldid=99631"