Gemstone irradiation: Difference between revisions
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The '''gemstone irradiation''' is a process in which a [[gemstone]] is artificially [[Irradiation|irradiated]] in order to enhance its optical properties. High levels of [[ionizing radiation]] can change the [[atomic structure]] of the gemstone's [[crystal lattice]], which in turn alters the optical properties within it.<ref name=Hurlbut_170> |
The '''gemstone irradiation''' is a process in which a [[gemstone]] is artificially [[Irradiation|irradiated]] in order to enhance its optical properties. High levels of [[ionizing radiation]] can change the [[atomic structure]] of the gemstone's [[crystal lattice]], which in turn alters the optical properties within it.<ref name=Hurlbut_170>Hurlbut & Kammerling (1991)</ref> As a result, the gemstone's color may be significantly altered or the visibility of its inclusions may be lessened. The process, widely practised in [[jewelry industry]],<ref>{{cite web | title = Gemstone Dedicated Gamma Irradiator Development | url = http://www.inac2007.com.br/dvd/pdf_dvd/E14_1248.pdf | first = Nelson M. | last = Omi | coauthors = Paulo R. Rela | publisher = ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR | year = 2007 | accessdate = November 30, 2008 | format = PDF }}</ref> is done in either a [[nuclear reactor]] for [[neutron]] bombardment, a [[particle accelerator]] for [[electron]] bombardment, or a [[gamma ray]] facility using the [[radioactive isotope]] [[cobalt-60]].<ref name=Hurlbut_170/><ref name=NRC>{{cite web | url = http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/irradiated-gemstones.html | title = Fact Sheet on Irradiated Gemstones | publisher = The U.S. [[Nuclear Regulatory Commission]] | date = February 2008 | accessdate = November 30, 2008 }} ''This article incorporates text from the source, which is in the [[public domain]].''</ref> The irradiation processes enabled the creation of certain gemstone colors that do not exist or are extremely rare in nature.<ref name=Hurlbut_170/> |
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==Radioactivity and regulations== |
==Radioactivity and regulations== |
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[[Image:Fancy colors.jpg|thumb|right|Irradiated natural diamonds]] |
[[Image:Fancy colors.jpg|thumb|right|Irradiated natural diamonds]] |
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The irradiation process can make gemstones slightly radioactive, particularly those treated in a nuclear reactor,<ref name=Hurlbut_172> |
The irradiation process can make gemstones slightly radioactive, particularly those treated in a nuclear reactor,<ref name=Hurlbut_172>Hurlbut & Kammerling (1991)</ref> so they are typically set aside for a couple of months to allow any residual radioactivity to decay.<ref name=NRC/> The first documented artificially irradiated gemstone is a [[diamond]] that became green after being buried in [[radium]] salts.<ref name=Hurlbut_158>Hurlbut & Kammerling (1991)</ref> This method produced a dangerously high degree of long-term residual radioactivity and has been discontinued,<ref name=Hurlbut_216>Hurlbut & Kammerling (1991)</ref> although radium-treated green diamonds are still occasionally found in markets and can be detected by a [[Geiger counter]] or making its [[autoradiograph]] using a [[photographic film]].<ref name=Hurlbut_216/> The concerns for possible health risks related to the residual radioactivity of the gemstones led to government regulations in many countries.<ref name=Hurlbut_170/> In the United States, the [[Nuclear Regulatory Commission]] (NRC) has set strict limits on the allowable levels of residual radioactivity before an irradiated gemstone can be distributed in the country.<ref name=NRC/> All neutron- or electron beam-irradiated gemstones must be tested by an NRC-licensee prior to release for sales.<ref name=NRC/> |
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==Types and results== |
==Types and results== |
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{{multiple image| align = right | direction = horizontal | header = | header_align = left/right/center | footer = Goshenite (left) and heliodor (right) | footer_align = left | image1 = Goshénite et mica muscovite (Chine)1.jpg | width1 = 133 | caption1 = | image2 = Heliodoorruw.jpg | width2 = 123 | caption2 = }} |
{{multiple image| align = right | direction = horizontal | header = | header_align = left/right/center | footer = Goshenite (left) and heliodor (right) | footer_align = left | image1 = Goshénite et mica muscovite (Chine)1.jpg | width1 = 133 | caption1 = | image2 = Heliodoorruw.jpg | width2 = 123 | caption2 = }} |
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The most commonly irradiated gemstone is [[topaz]], which becomes blue as a result of the exposure to radiation.<ref name=NRC/> Colorless [[beryl]]s (goshenite) become pure yellow when irradiated, which are called golden beryl or heliodor.<ref name=Hurlbut_170/> [[Pearl]]s are occasionally irradiated to produce gray blue or gray-to-black colors.<ref> |
The most commonly irradiated gemstone is [[topaz]], which becomes blue as a result of the exposure to radiation.<ref name=NRC/> Colorless [[beryl]]s (goshenite) become pure yellow when irradiated, which are called golden beryl or heliodor.<ref name=Hurlbut_170/> [[Pearl]]s are occasionally irradiated to produce gray blue or gray-to-black colors.<ref>Sofianides & Harlow (1991)</ref> Gemstones that have been subjected to artificial irradiation generally show no visible evidence of the process,<ref name=Hurlbut_127>Hurlbut & Kammerling (1991)</ref> although some diamonds irradiated in an [[electron beam]] may show color concentrations around the [[culet]] or along the keel line.<ref name=Hurlbut_127/> Some irradiation sources may produce mixtures of blue and yellow-to-brown colors in topaz, so a heating process is required as an additional step to remove the yellowish color.<ref>Sofianides & Harlow (1991)</ref> |
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==Color stability== |
==Color stability== |
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In some cases, the new colors induced by artificial irradiation may fade rapidly when exposed to light or heat,<ref name=Hurlbut_057> |
In some cases, the new colors induced by artificial irradiation may fade rapidly when exposed to light or heat,<ref name=Hurlbut_057>Hurlbut & Kammerling (1991)</ref> so some laboratories submit them to a "fade test" to determine color stability.<ref name=Hurlbut_057/> Sometimes colorless or pink beryls become deep blue upon irradiation, which are called Maxixe-type beryl. However, the color easily fades when exposed to heat or light, so it has no practical jewelry application.<ref name=Hurlbut_170/> |
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==Notes== |
==Notes== |
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{{reflist}} |
{{reflist}} |
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==References== |
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*{{cite book | title = Gemology | first = Cornelius S. | last = Hurlbut | coauthors = Robert C. Kammerling | publisher = Wiley-Interscience | isbn = 0471526673 | year = 1991 }} |
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*{{cite book | title = Gems and Crystals: From the American Museum of Natural History | first = Anna S. | last = Sofianides | coauthors = George E. Harlow | publisher = Simon & Schuster | isbn = 0671687042 | year = 1991 }} |
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[[Category:Gemstones|Irradiation]] |
[[Category:Gemstones|Irradiation]] |
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The gemstone irradiation is a process in which a gemstone is artificially irradiated in order to enhance its optical properties. High levels of ionizing radiation can change the atomic structure of the gemstone's crystal lattice, which in turn alters the optical properties within it.[1] As a result, the gemstone's color may be significantly altered or the visibility of its inclusions may be lessened. The process, widely practised in jewelry industry,[2] is done in either a nuclear reactor for neutron bombardment, a particle accelerator for electron bombardment, or a gamma ray facility using the radioactive isotope cobalt-60.[1][3] The irradiation processes enabled the creation of certain gemstone colors that do not exist or are extremely rare in nature.[1]
Radioactivity and regulations
The irradiation process can make gemstones slightly radioactive, particularly those treated in a nuclear reactor,[4] so they are typically set aside for a couple of months to allow any residual radioactivity to decay.[3] The first documented artificially irradiated gemstone is a diamond that became green after being buried in radium salts.[5] This method produced a dangerously high degree of long-term residual radioactivity and has been discontinued,[6] although radium-treated green diamonds are still occasionally found in markets and can be detected by a Geiger counter or making its autoradiograph using a photographic film.[6] The concerns for possible health risks related to the residual radioactivity of the gemstones led to government regulations in many countries.[1] In the United States, the Nuclear Regulatory Commission (NRC) has set strict limits on the allowable levels of residual radioactivity before an irradiated gemstone can be distributed in the country.[3] All neutron- or electron beam-irradiated gemstones must be tested by an NRC-licensee prior to release for sales.[3]
Types and results
1.jpg)
Goshenite (left) and heliodor (right)
The most commonly irradiated gemstone is topaz, which becomes blue as a result of the exposure to radiation.[3] Colorless beryls (goshenite) become pure yellow when irradiated, which are called golden beryl or heliodor.[1] Pearls are occasionally irradiated to produce gray blue or gray-to-black colors.[7] Gemstones that have been subjected to artificial irradiation generally show no visible evidence of the process,[8] although some diamonds irradiated in an electron beam may show color concentrations around the culet or along the keel line.[8] Some irradiation sources may produce mixtures of blue and yellow-to-brown colors in topaz, so a heating process is required as an additional step to remove the yellowish color.[9]
Color stability
In some cases, the new colors induced by artificial irradiation may fade rapidly when exposed to light or heat,[10] so some laboratories submit them to a "fade test" to determine color stability.[10] Sometimes colorless or pink beryls become deep blue upon irradiation, which are called Maxixe-type beryl. However, the color easily fades when exposed to heat or light, so it has no practical jewelry application.[1]
Notes
- ^ a b c d e f Hurlbut & Kammerling (1991)
- ^ Omi, Nelson M. (2007). "Gemstone Dedicated Gamma Irradiator Development" (PDF). ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR. Retrieved November 30, 2008.
{{cite web}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c d e "Fact Sheet on Irradiated Gemstones". The U.S. Nuclear Regulatory Commission. February 2008. Retrieved November 30, 2008. This article incorporates text from the source, which is in the public domain.
- ^ Hurlbut & Kammerling (1991)
- ^ Hurlbut & Kammerling (1991)
- ^ a b Hurlbut & Kammerling (1991)
- ^ Sofianides & Harlow (1991)
- ^ a b Hurlbut & Kammerling (1991)
- ^ Sofianides & Harlow (1991)
- ^ a b Hurlbut & Kammerling (1991)
References
- Hurlbut, Cornelius S. (1991). Gemology. Wiley-Interscience. ISBN 0471526673.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - Sofianides, Anna S. (1991). Gems and Crystals: From the American Museum of Natural History. Simon & Schuster. ISBN 0671687042.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help)