Ternary plot of different colors of Ag-Au-Cu alloys

While pure gold is yellow in color, colored gold can be developed into various colors. These colors are generally obtained by alloying gold with other elements in various proportions.

For example, alloys which are mixed 14 parts gold to 10 parts alloy create 14-karat gold, 18 parts gold to 6 parts alloy creates 18 karat, and so on. This is often expressed as the result of the ratio, i.e.: 14/24 equals 0.585 and 18/24 is 0.750. There are hundreds of possible alloys and mixtures, but in general the addition of silver will color gold white, and the addition of copper will color it red. A mix of around 50/50 copper and silver gives the range of yellow gold alloys the public is accustomed to seeing in the marketplace. A small amount (0.2%) of zinc can be added to harden the alloy.

The most common grades of gold, in addition to pure 24K, are 22K (92%), 18K (75%), 14K (58%) and 9K (38%).^[1]

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

• the Au-Ag-Cu system, producing white, yellow, green and red golds; typically malleable alloys
• the intermetallic compounds, producing blue and purple golds, as well as other colors. These are typically brittle but can be used as gems and inlays
• the surface oxide layers, such as black gold; mechanical properties depend on the bulk alloy, and the colored surface is prone to wear

White gold[link]

Rhodium-plated white gold wedding ring

White gold is an alloy of gold and at least one white metal, usually nickel, manganese or palladium. Like yellow gold, the purity of white gold is given in karats.

White gold's properties vary depending on the metals and proportions used. As a result, white gold alloys can be used for many different purposes; while a nickel alloy is hard and strong and therefore good for rings and pins, gold-palladium alloys are soft, pliable and good for white gold gemstone settings, sometimes with other metals like copper, silver, and platinum for weight and durability, although this often requires specialized goldsmiths. The term white gold is used very loosely in the industry to describe karat gold alloys with a whitish hue. Many believe that the color of the rhodium plating, which is seen on many commercial pieces, is actually the color of white gold. The term "white" covers a large spectrum of colors that borders or overlaps pale yellow, tinted brown, and even very pale rose. The jewelry industry often improves these off-white colors by rhodium plating.

A common white gold formulation consists of 90 wt.% gold and 10 wt.% nickel.^[1] 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.

Contact allergy[link]

About one out of eight people has an allergic reaction to the nickel in some white gold alloys when worn over long periods. A typical reaction is a minor skin rash.^[3] Because of this, many European countries do not use nickel white gold. White gold alloys made without nickel are less likely to be allergenic.

Rose, red, and pink gold[link]

Rose gold is a gold and copper alloy widely used for specialized jewelry. It is also known as pink gold and red gold. As it was popular in Russia at the beginning of the nineteenth century, it is also known as Russian gold, however, this term is now obsolete.

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. A common alloy for rose gold is 75% gold and 25% copper by mass (18 karat). Since rose gold is an alloy, there is no such thing as "pure rose gold".

A common formulation for red gold is 50% gold and 50% copper.^[1]

Up to 15% zinc can be added to copper-rich alloys to change their color to reddish yellow or dark yellow.^[2]

During ancient times, due to impurities in the smelting process, gold frequently turned a reddish color. This is why many Greco-Roman texts, and even many texts from the Middle Ages, describe gold as "red".^{[citation needed]}

Rose gold alloys[link]

The highest karat version of rose gold is also known as crown gold, which is 22 karat. Eighteen karat red gold may be made of 25% copper and 75% gold. For 18 karat rose gold, typically about 4% silver is added to 75% gold and 21% copper to give a rose color. 14 karat red gold is often found in the Middle East and contains 41.67% copper.

Rose gold in musical instruments[link]

High-end flutes are very commonly made of solid rose gold, the most common alloy being 14K, but 9K, 10K, 18K and 19.5K are also available from the major flute makers.

Spangold[link]

Some gold copper-aluminum alloys form a fine surface texture at heat treatment, yielding an interesting spangling effect. At cooling, they undergo a quasi-martensitic transformation from body centered cubic to body-centered tetragonal phase; the transformation does not depend on the cooling rate. A polished object is heated in hot oil to 150 - 200°C for 10 minutes then cooled below 20°C, forming a sparkly surface covered with tiny facets.

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

Green gold[link]

Green gold alloys are made by leaving the copper out of the alloy mixture and just using gold and silver. It actually appears as a greenish yellow rather than green. Eighteen karat green gold would therefore contain a mix of gold 75% and silver 25% (or 73% gold and 27% silver). Fired enamels adhere better to these alloys.

Green gold was known to Lydians as long ago as 860 BC under the name electrum, a naturally occurring alloy of silver and gold.^[1]

Cadmium can be added to gold alloys in amount of up to 4% to achieve green color. The alloy of 75% gold, 23% copper, and 2% cadmium yields light green 18ct gold. The alloy of 75% gold, 15% silver, 6% copper, and 4% cadmium yields a dark green alloy. Cadmium is, however, toxic.

Grey gold[link]

Grey gold alloys are made by adding silver, manganese and copper in specific ratios to the gold.^[4]

Black gold[link]

Black gold is a type of gold used in jewelry.^[5][6] Black colored gold can be produced by various methods:

• Electroplating, using black rhodium or ruthenium. Solutions that contain ruthenium give a slightly harder black coating than those that contain rhodium.^[7]
• Patination by applying sulfur and oxygen containing compounds.
• Plasma assisted chemical vapor deposition process involving amorphous carbon
• Controlled oxidation of gold containing chromium or cobalt (e.g. 75% gold, 25% cobalt^[1]).

A range of colors from brown to black can be achieved on copper-rich alloys by treatment with potassium sulfide.^[2]

Cobalt-containing alloys, e.g. 75% gold with 25% cobalt, form a black oxide layer with heat treatment at 700-950 °C. Copper, iron and titanium can be also used for such effect. Gold-cobalt-chromium alloy (75% gold, 15% cobalt, 10% chromium) yields surface oxide that's olive-tinted because of the chromium(III) oxide content, is about 5 times thinner than Au-Co and has significantly better wear resistance. The gold-cobalt alloy consists of a gold-rich (about 94% Au) and cobalt-rich (about 90% Co) phases; the cobalt-rich phase grains are capable of oxide layer formation on their surface.^[2]

More recently a laser technique has been developed that renders the surface of metals deep black. A femtosecond laser pulse deforms the surface of the metal forming nanostructures. The immensely increased surface area can absorb virtually all the light that falls on it thus rendering it deep black.^[8]

Purple and blue golds[link]

Gold-aluminium phase diagram

Purple gold (also called amethyst gold and violet gold) is an alloy of gold and aluminum 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, as it is an intermetallic compound instead of a malleable alloy, and a sharp blow may cause it to shatter.^[7] It is therefore usually machined and faceted to be used as a "gem" in conventional jewelry rather than by itself. At lower content of gold, the material is composed of the intermetallic and an aluminium-rich solid solution phase. At 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 is an alloy of gold and indium.^[7] It contains 46% gold (about 12 ct) and 54% indium,^[1] 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.^[10]

All the AuX₂ intermetallics have crystal structure of CaF₂ and therefore are brittle.^[2] Deviation from the stoichiometry results in loss of color. Slightly nonstoichiometric compositions are however used, to achieve a fine-grained two- or three-phase microstructure with reduced brittleness. A small amount of palladium, copper or silver can be added to achieve a less brittle microstructure.^[10]

The intermetallic compounds tend to have poor corrosion resistance. The less noble elements are leached to the environment, and a gold-rich surface layer is formed. Direct contact of blue and purple gold elements with skin should be avoided as exposition to sweat may result in metal leaching and discoloration of the metal surface.^[10]

A surface plating of blue gold on karat gold or sterling silver can be achieved by a gold plating of the surface, followed by indium plating, with layer thickness matching the 1:2 atomic ratio. A heat treatment then causes interdiffusion of the metals and formation of the required intermetallic compound.

Oxide layer blue gold[link]

Blue gold can be achieved by formation of an oxide layer on 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]

Gold of purity 20–23 carat, when alloyed with ruthenium, rhodium and three other elements and heat-treated at 1800 °C, forms a 3–6 micrometers thick surface layer with a rich sapphire blue color.^[2]

See also[link]

• Shakudō
• Tumbaga
• Electrum
• Crown gold
• List of alloys

References[link]

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (February 2009)

This article is about a term used for black people like African-Americans. For the term used to describe an ethnic group in Southern Africa see Coloured. For other uses see Color (disambiguation). For the dc Talk song, see Colored People (song).

Colored is a term once widely used in the United States to describe black people (i.e., persons of sub-Saharan African ancestry; members of the "Black race") and Native Americans.^[1] It should not be confused with the more recent term people of color, which attempts to describe all "non-white peoples," not just black people.

The term "colored" appeared in North America during the colonial era. A "colored" man halted a runaway carriage that was carrying President John Tyler on March 4, 1844.^{[citation needed]} In 1851 an article in the New York Times referred to the "colored population".^[2] In 1863, the War Department established the "Bureau of Colored Troops." The first 12 Census counts in the U.S. enumerated "colored" people, who totaled nine million in 1900. The Census counts of 1910–1960 enumerated "negroes."

Today it is generally no longer regarded as a politically correct term. This history term is used in the acronym NAACP. Carla Sims, communications director for the NAACP in Washington, D.C., said "The term 'colored' is not derogatory, {however, all have color}, {[the NAACP]} chose the word 'colored' because it was the most positive description commonly used at that time. It's outdated and antiquated but not offensive." ^[3]

In other English-speaking countries, the term has varied meanings. In South Africa, Namibia, Zambia and Zimbabwe, the term Coloured refers both to a specific ethnic group of complex mixed origins, which is considered neither black nor white, and in other contexts to people of mixed race; in neither context is its usage considered derogatory. In British usage the term can refer to those of Asian, Middle-Eastern or African descent and is not usually considered derogatory, though more accurate terms are preferable (particularly if referring to a single ethnicity).

See also[link]

References[link]

1. ^ W. David Baird et al. (2009-01-05). ""We are all Americans", Native Americans in the Civil War". Native Americans.com. http://oha.alexandriava.gov/fortward/special-sections/americans/. Retrieved 2009-01-05. 
2. ^ New York Times. September 18, 1851. p. 3. 
3. ^ "NAACP says no big deal". Mercury News. http://blogs.mercurynews.com/aei/2008/11/12/lohan-calls-obama-colored-naacp-says-no-big-deal#ftnb. 

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2010)

Adolph Herman Joseph Coors, Sr.
Adolph Coors statue in downtown Golden, Colorado; he was the grandfather of brewer Joseph Coors.
Born	February 4, 1847 Barmen
Died	June 5, 1929(1929-06-05) (aged 82) Virginia Beach, Virginia
Occupation	Brewer
Parents	Joseph Kuhrs (c1820-1862) Helena Hein (c1820-1862)

Adolph Herman Joseph Coors, Sr. (February 4, 1847 – June 5, 1929) was a brewman who started the Adolph Coors Company in Golden, Colorado in 1873.

Early years[link]

Adolph Coors was born in Barmen in Rhenish Prussia on February 4, 1847, the son of Joseph Kuhrs (c1820-1862) and Helena Hein (c1820-1862). He was apprenticed at age thirteen to the book and stationery store of Andrea & Company in nearby Ruhrort from November 1860 until June 1862. His mother died on April 2, 1862. The Kuhrs family moved to Dortmund, Westphalia. In July 1862, Adolph was apprenticed for a three year period at a brewery owned by Henry Wenker in Dortmund. He was charged a fee for his apprenticeship, so he worked as a bookkeeper to pay for it. His father died on November 24, 1862. Orphaned, Adolph completed his apprenticeship and continued to work as a paid employee at the Wenker Brewery until May 1867. He then worked at breweries in Kassel, Berlin, and Uelzen in Germany. Early in 1868, he immigrated to the United States. He sailed from Hamburg to New York City and then moved to Chicago arriving on May 30, 1868. His name was changed from "Kuhrs" to "Coors". He worked in the spring as a laborer, and during the summer he worked as a brewer. In the fall and winter he worked as a fireman, loading coal into the firebox of a steam engine. In the spring and summer of 1869 he worked as an apprentice bricklayer and a stone cutter. He became foreman of John Stenger's brewery on August 11, 1869, in Naperville, Illinois, about 35 miles west of Chicago. He resigned from Stenger's brewery on January 22, 1872, and arrived in Denver in April. He worked in Denver as a gardener for a month, then on May 1, 1872 he purchased a partnership in the bottling firm of John Staderman. In the same year he bought and assumed control of the entire business.^{[1][not specific enough to verify]}

Golden Brewery[link]

On November 14, 1873, Coors and the Denver confectioner Jacob Schueler purchased the abandoned Golden City Tannery and converted it to the Golden Brewery. By February 1874 they were producing beer for sale. In 1880 Coors purchased Schueler's interest, and the brewery remained majority family-owned as of 2006^[update]. When Prohibition was begun in Colorado in 1916, he converted his brewery to make malted milk. The company also manufactured porcelain and ceramic products made from clay mined in Golden. The Coors Porcelain division has since split off, and is now known as CoorsTek.

Marriage and Family[link]

Immediate Family[link]

On April 12, 1879 Adolph Coors married Louisa Webber, the daughter of the superintendent of the Denver & Rio Grande Railroad maintenance shops. They were married at the Coors home on the brewery grounds. Adolph and Louisa raised three sons and three daughters to adulthood, with two children dying in infancy. Louise was born on March 2, 1880, and was nicknamed Lulu among her many friends. Their second child was Augusta, born in 1881, and was known by her nickname of Gussie. The fifth and third surviving child was Adolph Coors Jr., on January 12, 1884. Bertha Coors was born on June 24, 1886, and Grover C. Coors was born in 1888. The last addition to the family, Herman Frederick Coors, came on July 24, 1890, when while the family was on vacation to Berlin.

All of the daughters attended the Wolcott School for Girls in Denver. Louise married Henry F. Kugeler at the Coors Mansion, and Augusta married Herbert E. Collbran there on October 5, 1905. At the time, Transcript editor George West wrote "Miss Coors is a native Golden girl and proud of it. She is pretty and talented, and by her universally pleasant and courteous demeanor has endeared herself to all the people of her native town." She and her husband moved to Korea, where Herbert was the son of the nation's transportation advisor and held an important position with the governmental railways. It is possible that with the advent of international shipping of Coors beer, which began in Korea in 1908, was directly related to the family's presence there. Adolph Jr., Grover and Herman all graduated from Cornell University, and returned to take positions helping run the family operations. Adolph Jr. was married to Alice May Kistler at the Kistler home, and the family lived in Denver. Grover and Gertrude Coors were married at the Coors Mansion. Bertha, who became an accomplished equestrienne and safari hunter, was married to Harold S. Munroe on January 8, 1911 at the Coors Mansion. The couple moved to Mexico where Harold worked in gold mining operations. Herman Coors married Janet Ferrin and stayed in Golden, and worked in the family's porcelain manufacturing operations. In 1926 he moved to Inglewood, California where he set up his own porcelain plant, the H.F. Coors Company.

Siblings[link]

Adolph Coors is known to have had at least two siblings, a sister and younger brother William Coors, who was born in Dortmund, Germany in 1849. William followed his brother to America in 1870 and took the same respelling of the family name. He made his way to Chicago where he made a good living as a cabinet maker, and arrived in Golden by the mid-1870s. He took a good position of employment at his brother's brewery, in which employ he remained for the rest of his life. Following further in his brother's footsteps, William married Louisa's sister Mary in 1881, and ten years later moved to Denver where he had charge of the Coors interests in that city. The couple had three daughters, two of whom were Mattie and Helena. William Coors died on December 30, 1923 and is buried at the Golden Cemetery. Upon his death the Colorado Transcript described him as "a genial, accommodating man, and had many friends in Golden, Denver and elsewhere." His oldest daughter married William J. Gilbert and the second married Charles Nitschke.

Death by suicide[link]

He took his own life on June 5, 1929, at the Cavalier Hotel in Virginia Beach, Virginia when he jumped to his death from the hotel window.^[2]

See also[link]

Biography portal

• Adolph Coors III
• Pete Coors
• August Anheuser Busch, Sr., brewer who also took his own life

References[link]

External links[link]