Carat (purity)
Overview
 
The karat or carat is a unit of purity for gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 alloys.
Karat purity is measured as 24 times the purity by mass:

where
is the karat rating of the material,
is the mass of pure gold or platinum in the material, and
is the total mass of the material.


Therefore, 24-Karat gold is fine (99.9% Au w/w), 18-Karat gold is 18 parts gold 6 parts another metal (forming an alloy), 12-Karat gold is 12 parts gold (12 parts another metal), and so forth.

In England, the Karat was divisible into four grains, and the grain was divisible into four quarts.
Encyclopedia
The karat or carat is a unit of purity for gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 alloys.

Measure

Karat purity is measured as 24 times the purity by mass:

where
is the karat rating of the material,
is the mass of pure gold or platinum in the material, and
is the total mass of the material.


Therefore, 24-Karat gold is fine (99.9% Au w/w), 18-Karat gold is 18 parts gold 6 parts another metal (forming an alloy), 12-Karat gold is 12 parts gold (12 parts another metal), and so forth.

In England, the Karat was divisible into four grains, and the grain was divisible into four quarts. For example, a gold alloy of fineness (that is, 99.2% purity) could have been described as being 23-Karat, 3-grain, 1-quart gold.

The Karat system is increasingly being complemented or superseded by the millesimal fineness
Millesimal fineness
Millesimal fineness is a system of denoting the purity of platinum, gold and silver alloys by parts per thousand of pure metal by mass in the alloy. For example, an alloy containing 75% gold is denoted as "750". Many European countries use decimal hallmark stamps Millesimal fineness is a system of...

 system, in which the purity of precious metal
Precious metal
A precious metal is a rare, naturally occurring metallic chemical element of high economic value.Chemically, the precious metals are less reactive than most elements, have high lustre, are softer or more ductile, and have higher melting points than other metals...

s is denoted by parts per thousand of pure metal in the alloy.

Derivation

"Karat" is a variant of "carat". First attested in English in the mid-15th century, the word "carat" came from Middle French
Middle French
Middle French is a historical division of the French language that covers the period from 1340 to 1611. It is a period of transition during which:...

 carat, in turn from Italian carato, which came from Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...

 qīrāṭ (قيراط), which came from Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 kerátion (κεράτιον) meaning carob seed (literally "small horn")
(diminutive of κέρας - keras, "horn")
and was a unit of weight
though it was not likely used to measure gold in classical times.

In 309 CE, Roman Emperor
Roman Emperor
The Roman emperor was the ruler of the Roman State during the imperial period . The Romans had no single term for the office although at any given time, a given title was associated with the emperor...

 Constantine I
Constantine I
Constantine the Great , also known as Constantine I or Saint Constantine, was Roman Emperor from 306 to 337. Well known for being the first Roman emperor to convert to Christianity, Constantine and co-Emperor Licinius issued the Edict of Milan in 313, which proclaimed religious tolerance of all...

 began to mint
Mint (coin)
A mint is an industrial facility which manufactures coins for currency.The history of mints correlates closely with the history of coins. One difference is that the history of the mint is usually closely tied to the political situation of an era...

 a new gold coin solidus
Solidus (coin)
The solidus was originally a gold coin issued by the Romans, and a weight measure for gold more generally, corresponding to 4.5 grams.-Roman and Byzantine coinage:...

that was of a libra (Roman pound) of gold
equal to a mass of 24 siliqua
Siliqua
The siliqua is the modern name given to small, thin, Roman silver coins produced from 4th century and later. When the coins were in circulation, the Latin word siliqua was a unit of weight defined as one-twentyfourth of the weight of a Roman solidus .The term siliqua comes from the siliqua graeca,...

, where each siliqua (or carat
Carat (mass)
The carat is a unit of mass equal to 200 mg and is used for measuring gemstones and pearls.The current definition, sometimes known as the metric carat, was adopted in 1907 at the Fourth General Conference on Weights and Measures, and soon afterward in many countries around the world...

) was of a libra.
This is believed to be the origin of the value of the karat.

Terminology

22/22K - a quality mark indicating the purity of gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 most popularly used in India. This purity was adapted and practiced by the big jewellers and was later passed to jewel smiths. The first 22 signifies the "Skin purity", the purity of the top layer of the gold jewelry, and the second 22 signifies that after melting purity of the gold jewellery will be 22-karat, or 91.67% of pure gold. This system is used to show consistency in the quality of the gold.

This practice was pioneered and introduced in the early mid-1980s by Nemichand Bamalwa & Sons of Kolkata, India, sparking a revolution in India, as it forced jewellers to indicate correctly the after-melting purity. Heightened consumer awareness made it a most sought-after stamp or quality mark.

This symbol or stamp can be found in Asian countries like India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

, Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

, Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

, Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...

, Yemen
Yemen
The Republic of Yemen , commonly known as Yemen , is a country located in the Middle East, occupying the southwestern to southern end of the Arabian Peninsula. It is bordered by Saudi Arabia to the north, the Red Sea to the west, and Oman to the east....

, and Persian Gulf
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...

 countries.
Region Typical caratage (fineness)
International caratages of gold jewellery
Arabic countries
Arab world
The Arab world refers to Arabic-speaking states, territories and populations in North Africa, Western Asia and elsewhere.The standard definition of the Arab world comprises the 22 states and territories of the Arab League stretching from the Atlantic Ocean in the west to the Arabian Sea in the...

, Far East (China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...

, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

)
24-karat "Chuk Kam" (99.0% min)
Arabic countries
Arab world
The Arab world refers to Arabic-speaking states, territories and populations in North Africa, Western Asia and elsewhere.The standard definition of the Arab world comprises the 22 states and territories of the Arab League stretching from the Atlantic Ocean in the west to the Arabian Sea in the...

, Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

, and Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

 
22-karat (91.6%)
Arabic countries
Arab world
The Arab world refers to Arabic-speaking states, territories and populations in North Africa, Western Asia and elsewhere.The standard definition of the Arab world comprises the 22 states and territories of the Arab League stretching from the Atlantic Ocean in the west to the Arabian Sea in the...

 in the Persian Gulf region
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...

 
21-carat (87.5%), 18-karat (75.0%) in most Egypt
Europe - Southern / Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

 
19.2-karat (80.0%)
Europe - Southern / Mediterranean  18-karat (75.0%)
Europe - Northern Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 etc.
8- to 18-karat (33.3 - 75.0%)
Russia/former USSR  9- (37.5%) and 14-karat/old 583 and new 585 проба (58.5%)
United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 
9-karat to 22 karat (37.5-91.6%)
United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 
10-karat to 18-karat (41.7-75%)

Chuk Kam

Chuk Kam (足金) in Cantonese means pure gold, literally "exact gold". It is defined as 99.0% gold minimum with a 1.0% negative tolerance allowed. The quality of gold is guaranteed with a "Certificate of Gold" upon purchases in Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...

 and Macau
Macau
Macau , also spelled Macao , is, along with Hong Kong, one of the two special administrative regions of the People's Republic of China...

. The related term "千足" and "万足" meaning "thousand exact" and "ten thousand exact" is also used for purity of 99.9% and 99.99% respectively. This is because the impurity is at most 1 in 1,000 in the case of 99.9% or 1 in 10,000 for 99.99%.

United States of America

The USA Federal Trade Commission
Federal Trade Commission
The Federal Trade Commission is an independent agency of the United States government, established in 1914 by the Federal Trade Commission Act...

 (FTC) has standardized the karat markings used within its boundaries for almost 7 decades now. Under these regulations, items 10-karat or greater are to be stamped with either "K" or "Kt." Decimal markings are also an option under the CFTC regulations.

Under-karating is against the law in the United States of America. There are specific mandated consequences including fines, etc., based upon the severity of the infraction(s).

In addition, there is a set of tolerances to the required karat markings in the USA (always designated with a "K" and never a "C") depending upon the use of various soldering requirements when setting stones, mounting crowns, or creating prongs for 3 examples.

See also

Gold alloys
  • Colored gold
    Colored gold
    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....

  • Electrum
    Electrum
    Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. It has also been produced artificially. The ancient Greeks called it 'gold' or 'white gold', as opposed to 'refined gold'. Its color ranges from pale to bright yellow, depending on the...

  • Rose gold
  • Tumbaga
    Tumbaga
    Tumbaga was the name given by Spaniards to a non-specific alloy of gold and copper which they found in widespread use in pre-Columbian Mesoamerica and South America.-Composition and properties:...

  • White gold
    White Gold
    White Gold is a 2003 Russian action film directed by Viktor Ivanov from a screenplay by John Jopson and Viktor Ivanov. The story begins with the actual events of 1919 when a White Army train carrying the bulk of Czar Nicholas' gold reserves arrives empty at Siberia's Irkutsk station...


  • Gold coin
    Gold coin
    A gold coin is a coin made mostly or entirely of gold. Gold has been used for coins practically since the invention of coinage, originally because of gold's intrinsic value...

  • Platinum coin
    Platinum coin
    Platinum coins are a form of currency. Platinum has an international currency symbol under ISO 4217 of XPT. The issues of legitimate platinum coins were initiated by Spain in Spanish-colonized America in the 18th century and continued by the Russian Empire in the 19th century...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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