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Colored gold (9802 views - Material Database)

Pure gold is slightly reddish yellow in color, but colored gold in various other colors can be produced. Colored golds can be classified to three groups: Alloys with silver and copper in various proportions, producing white, yellow, green and red golds; typically malleable alloys Intermetallic compounds, producing blue and purple golds, as well as other colors. These are typically brittle but can be used as gems and inlays Surface treatments such as oxide layers Pure 100% gold is 24 karat by definition, so all colored golds are less than this, with the common being 18K (75%), 14K (58%), and 9K (38%).
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Colored gold

Colored gold

Colored gold

Licensed under GNU Free Documentation License (Original image: Metallos).

Pure gold is slightly reddish yellow in color,[1] but colored gold in various other colors can be produced.

Colored golds can be classified to three groups:[2]

  • Surface treatments such as oxide layers



White gold



A common white gold formulation consists of 90 wt.% gold and 10 wt.% nickel.[3] Copper can be added to increase malleability.[2]

The strength of gold–nickel–copper alloys is caused by formation of two phases, a gold-rich Au–Cu, and a nickel-rich Ni–Cu, and the resulting hardening of the material.[2]

The alloys used in jewelry industry are gold–palladium–silver and gold–nickel–copper–zinc. Palladium and nickel act as primary bleaching agents for gold; zinc acts as a secondary bleaching agent to attenuate the color of copper.

The nickel used in some white gold alloys can cause an allergic reaction when worn over long periods (also notably on some wrist-watch casings).[4] This reaction, typically a minor skin rash from nickel dermatitis, occurs in about one out of eight people and because of this, many countries do not use nickel in their white gold formulations.

Rose, red, and pink gold

Rose gold is a gold and copper alloy[5] widely used for specialized jewelry. Rose gold, also known as pink gold and red gold, was popular in Russia at the beginning of the nineteenth century, and was also known as Russian gold although this term is now obsolete. Rose gold jewelry is becoming more popular in the 21st century and is commonly used for wedding rings, bracelets, and other jewelry.

Although the names are often used interchangeably, the difference between red, rose, and pink gold is the copper content: the higher the copper content, the stronger the red coloration. Pink gold uses the least copper, followed by rose gold, with red gold having the highest copper content. Examples of the common alloys for 18K rose gold, 18K red gold, and 18K pink gold:

  • 18K Red gold: 75% gold, 25% copper
  • 18K Rose gold: 75% gold, 22.25% copper, 2.75% silver
  • 18K Pink gold: 75% gold, 20% copper, 5% silver
  • 12K Red gold: 50% gold and 50% copper.[3]



Crown gold


High-end flutes are very commonly made of solid rose gold, the most common alloy being 14K.[6]



The alloy of 76% gold, 19% copper, and 5% aluminium yields a yellow color; the alloy of 76% gold, 18% copper and 6% aluminium is pink.[2]

Green gold

Green gold was known to Lydians as long ago as 860 BC under the name electrum, a naturally occurring alloy of silver and gold.[3] It actually appears as greenish-yellow rather than green. Fired enamels adhere better to these alloys.

Cadmium can also be added to gold alloys but there are health concerns regarding its use.[7] The alloy of 75% gold, 23% copper, and 2% cadmium yields light-green 18-karat gold. The alloy of 75% gold, 15% silver, 6% copper, and 4% cadmium yields a dark-green alloy.

Grey gold

Grey gold alloys are usually made from gold and palladium. A cheaper alternative which does not use palladium is made by adding silver, manganese and copper in specific ratios to the gold.[8]




Purple gold

Purple gold (also called amethyst gold and violet gold) is an alloy of gold and aluminium rich in gold-aluminium intermetallic (AuAl2). Gold content in AuAl2 is around 79% and can therefore be referred to as 18 karat gold. Purple gold is more brittle than other gold alloys, (a serious fault when it forms in electronics[10]), as it is an intermetallic compound instead of a malleable alloy, and a sharp blow may cause it to shatter.[11] It is therefore usually machined and faceted to be used as a "gem" in conventional jewelry rather than by itself. At a lower content of gold, the material is composed of the intermetallic and an aluminium-rich solid solution phase. At a higher content of gold, the gold-richer intermetallic AuAl forms; the purple color is preserved to about 15% of aluminium. At 88% of gold the material is composed of AuAl and changes color. The actual composition of AuAl2 is closer to Al11Au6 as the sublattice is incompletely occupied.[2]

Blue gold

Blue gold is an alloy of gold and either gallium or indium.[11] Gold-indium contains 46% gold (about 11 karat) and 54% indium,[3] forming an intermetallic compound AuIn2. While several sources remark this intermetallic to have "a clear blue color",[2] in fact the effect is slight: AuIn2 has CIE LAB color coordinates of 79, −3.7, −4.2[9] which appears roughly as a greyish color. With gallium, gold forms an intermetallic AuGa2 (58.5% Au, 14ct) which has slighter bluish hue. The melting point of AuIn2 is 541 °C, for AuGa2 it is 492 °C. AuIn2 is less brittle than AuGa2, which itself is less brittle than AuAl2.[9]


Surface treatments

Black gold

Black gold is a type of gold used in jewelry.[12][13] Black-colored gold can be produced by various methods:



More recently, black gold can be formed by creating nanostructures on the surface. A femtosecond laser pulse deforms the surface of the metal, creating an immensely increased surface area which absorbs virtually all the light that falls on it, thus rendering it deep black,[14] but this method is used in high technology applications rather than for appearance in jewelry.

Blue gold

Oxide layers can also be used to obtain blue gold from and an alloy of 75% gold, 24.4% iron, and 0.6% nickel; the layer forms on heat treatment in air between 450–600 °C.[2]

A rich sapphire blue colored gold of 20–23K can also be obtained by alloying with ruthenium, rhodium and three other elements and heat-treating at 1800 °C, to form the 3–6 micrometers thick colored surface oxide layer.[2]

See also

AlGaAlnico알루미늄알루미늄 합금알루미늄 청동Aluminium-lithium alloyArsenical bronzeArsenical copperBell metal베릴륨베릴륨구리Billon (alloy)BirmabrightBismanol비스무트황동청동Calamine brassChinese silver크로뮴Chromium hydride코발트Constantan구리Copper hydrideCopper–tungstenCorinthian bronzeCunife백동Cymbal alloysDevarda's alloy두랄루민Dutch metal호박금Florentine bronzeGalfenolGalinstan갈륨Gilding metal유리GlucydurGuanín (bronze)GunmetalHepatizonHiduminiumHydronalium인듐ItalmaMagnalium마그네슘ManganinMegalliumMelchior (alloy)머큐리MolybdochalkosMuntz metal니크롬니켈양은노르딕 골드OrmoluPhosphor bronzePinchbeck (alloy)플라스틱Plexiglas플루토늄칼륨로듐Rose's metal사마륨스칸듐Shakudō나트륨Speculum metal스테인리스강강철StelliteStructural steel주석 (원소)타이타늄TombacTumbaga우라늄Vitallium우드 합금Y alloy아연지르코늄RhoditeCrown goldElinvarField's metalFernicoFerroalloy페로세륨FerrochromeFerromanganeseFerromolybdenumFerrosiliconFerrotitaniumFerrouraniumInvar주철Iron–hydrogen alloy선철Kanthal (alloy)KovarStaballoySpiegeleisenBulat steelCrucible steel41xx steel다마스쿠스 강MangalloyHigh-speed steelMushet steelMaraging steelHigh-strength low-alloy steelReynolds 531Electrical steelSpring steelAL-6XNCelestriumAlloy 20Marine grade stainlessMartensitic stainless steelSanicro 28Surgical stainless steelZeron 100Silver steelTool steelWeathering steelWootz steel땜납TerneType metalElektron (alloy)아말감Magnox (alloy)AlumelBrightrayChromelHaynes InternationalInconelMonelNicrosilNisilNickel titaniumMu-metal퍼멀로이SupermalloyNickel hydridePlutonium–gallium alloy나크Mischmetal리튬Terfenol-DPseudo palladiumScandium hydrideSamarium–cobalt magnetArgentium sterling silverBritannia silverDoré bullionGoloidPlatinum sterlingShibuichi스털링 실버Tibetan silverTitanium Beta CTitanium alloyTitanium hydrideGum metalTitanium goldTitanium nitride배빗메탈Britannia metal퓨터Queen's metalWhite metalUranium hydrideZamakZirconium hydride수소헬륨붕소질소산소플루오린메테인Mezzanine원자안료잉크


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