Jump to content

Fineness

From Wikipedia, the free encyclopedia
Not to be confused withFineness ratio.

Thefinenessof aprecious metalobject (coin, bar, jewelry, etc.) represents the weight offine metaltherein, in proportion to the total weight which includesalloyingbase metalsand anyimpurities.Alloy metals are added to increasehardnessand durability ofcoinsandjewelry,alter colors, decrease the cost per weight, or avoid the cost of high-purity refinement. For example,copperis added to the precious metalsilverto make a more durable alloy for use in coins, housewares and jewelry. Coin silver, which was used for makingsilver coinsin the past, contains 900 ‰ silver and 100 ‰ copper, bymass.Sterling silvercontains 925 ‰ silver and 75 ‰ of other metals, usually copper, by mass.

Various ways of expressing fineness have been used and two remain in common use:millesimal finenessexpressed in units ofparts per 1,000[1]andkaratsorcaratsused only forgold.Karats measure the parts per 24, so that 18 karat =18⁄24= 750 ‰ and 24 karat gold is considered 100% gold.[2]

Millesimal fineness

[edit]

Millesimal fineness is a system of denoting the purity ofplatinum,goldandsilveralloysbyparts per thousandof 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 (i.e., "585", "750", etc.) rather than "14 k", "18 k", etc., which is used in the United Kingdom and United States.

It is an extension of the older karat system of denoting the purity of gold by fractions of 24, such as "18 karat" for an alloy with 75% (18 parts per 24) pure gold by mass.

The millesimal fineness is usually rounded to a three figure number, particularly where used as ahallmark,and the fineness may vary slightly from the traditional versions of purity.

Here are the most common millesimal finenesses used forprecious metalsand the most common terms associated with them.

Platinum

[edit]
  • 999.95: what most dealers would buy as if 100% pure; the most common purity for platinum bullion coins and bars
  • 999—threeninesfine
  • 950: the most common purity for platinum jewelry
  • 900—one nine fine
  • 850
  • 750

Gold

[edit]
1troy ounceof four nines fine gold (999.9)
  • 999.999—sixninesfine:The purest gold ever produced. Refined by thePerth Mintin 1957.[3][4]
  • 999.99—five nines fine:The purest type of gold currently produced; theRoyal Canadian Mintregularly produces commemorative coins in this fineness, including the world's largest, at 100 kg.[5]
  • 999.9—four nines fine:Most popular. E.g. ordinaryCanadian Gold Maple LeafandAmerican Buffalocoins.
  • 999—24 karat,also occasionally known asthree nines fine:e.g.,Chinese Gold Pandacoins.
  • 995: The minimum allowed inGood Deliverygold bars.
  • 990—two nines fine
  • 986—Ducatfineness:Formerly used by Venetian and Holy Roman Empire mints; still in use in Austria and Hungary.
  • 958.3—23 karat
  • 916—22 karat:Crown gold.Historically the most widely used fineness for gold bullion coins, such as the oldest AmericanEagledenominations from 1795–1833. Currently used forBritish Sovereigns,South African Krugerrands,and the modern (1986—present)American Gold Eagles.
  • 900—one nine fine:American Eagle denominations for 1837–1933; currently used inLatin Monetary Unionmintage (e.g. French and Swiss "Napoleon coin"20 francs).
  • 899—American Eagles briefly for 1834—1836.
  • 834—20 karat
  • 750—18 karat:In Spainoro de primera ley(first law gold).
  • 625—15 karat
  • 585—14 karat
  • 583.3—14 karat:In Spainoro de segunda ley(second law gold).
  • 500—12 karat
  • 417—10 karat:Lowest legal solid gold karat made in the US prior to the August 2018 revision of the FTC Guides (Now 1 karat is legal).
  • 375—9 karat:Minimum standard for gold in some of the Commonwealth realms: Australia, Canada, New Zealand, UK, etc. It is also the minimum in Austria, Ireland, Portugal and France.
  • 333—8 karat:Minimum standard for gold in Germany after 1884.[6]It is also the minimum for Denmark, Greece and Mexico.
  • 1 karat:Legal minimum for gold in the US since the revision of the FTC Guides of August 2018.

Silver

[edit]
See also:Silver standards
A 2019American Silver Eaglebullion coinwith a fineness of 999 (three nines fine), together with aWalking Liberty half dollarwith a fineness of 900 (one nine fine); this latter alloy is also often referred to as90% silverorcoin silver.
  • 999.99—five nines fine:The purest silver ever produced. This was achieved by the Royal Silver Company of Bolivia.[7]
  • 999.9—fourninesfine:ultra-fine silver used by the Royal Canadian Mint for theirSilver Maple Leafand other silver coins
  • 999—fine silverorthree nines fine:used inGood Deliverybullion bars and most currentsilver bullion coins.Used in U.S. silvercommemorative coinsand silverproof coinsstarting in 2019.[8]
  • 980: common standard used in Mexico ca. 1930–1945
  • 958: (23⁄24)Britannia silver[9]
  • 950:French 1st Standard
  • 947.9: 91zolotnikRussian silver
  • 935: Swiss standard for watchcases after 1887, to meet the BritishMerchandise Marks Actand to be of equal grade to 925 sterling. Sometimes claimed to have arisen as a Swiss misunderstanding of the standard required for British sterling. Usually marked with three Swiss bears.
  • 935: used in the Art Deco period in Austria and Germany. Scandinavian silver jewellers used 935 silver after the 2nd World War
  • 925: (37⁄40)Sterling silver.The UK has used this alloy from the early 12th century. Equivalent toplata de primera leyin Spain (first law silver)
  • 917: a standard used for the minting of Indian silver (rupees), during the British raj and for some coins during the first Brazilian Republic.
  • 916: 88 zolotnik Russian silver
  • 900:oneninefine,coin silver,or90% silver:e.g.Flowing Hairand 1837–1964 U.S. silver coins. Also used in U.S. silvercommemorative coinsand silverproof coins1982–2018.
  • 892.4: US coinage1485⁄1664fine "standard silver" as defined by theCoinage Act of 1792:e.g.Draped BustandCapped BustU.S. silver coins (1795–1836)
  • 875: 84 zolotnik is the most common fineness for Russian silver. Swiss standard, commonly used for export watchcases (also 800 and later 935).
  • 868: 831⁄3zolotnik. Imperial Russian coinage between 1797[10]and 1885.[11]
  • 835: A standard predominantly used in Germany after 1884, and for some Dutch silver; and for the minting of coins in countries of theLatin Monetary Union
  • 833: (5⁄6) a common standard for continental silver especially among the Dutch, Swedish, and Germans
  • 830: A common standard used in older Scandinavian silver
  • 800: The minimum standard for silver in Germany after 1884; the French 2nd standard for silver; "plata de segunda ley" in Spain (second law silver); Egyptian silver; Canadian silver circulating coinage from 1920-1966/7[12]Used for the outer cladding of UShalf dollarsbetween 1965 and 1970, and commemorative issueEisenhower dollarsbetween 1971 and 1978 (cores are 20.9% silver)
  • 750: An uncommon silver standard found in older German, Swiss andAustro-Hungariansilver
  • 720: Decoplata:[13]many Mexican and Dutch silver coins use this standard, as well as some coins from Portugal's former colonies,[14]Japan,[15]Uruguay,[16]Ecuador, Egypt, and Morocco.
  • 600: Used in some examples of postwarJapanesecoins,such as the 1957-1966100 yen coin
  • 500: Standard used for making British coinage 1920–1946 as well as Canadian coins from 1967-1968, and some coins from Colombia and Brazil.
  • 350: Standard used for USJefferson "war nickels"minted between 1942 and 1945.

Carat

[edit]
"Karat" redirects here. For other uses, seeKarat (disambiguation).

Thecarat(UK spelling, symbolcorCt) orkarat(US spelling, symbolkorKt)[17][18]is a fractional measure of purity forgoldalloys,in parts fine per 24 parts whole. The carat system is a standard adopted by US federal law.[19]

Mass

[edit]
C= 24 × (Mg/Mm)

where

Cis the carat rating of the material,
Mgis the mass of pure gold in the alloy, and
Mmis the total mass of the material.

24-carat gold is pure (while 100% purity is very difficult to attain, 24-carat as a designation is permitted in commerce for a minimum of 99.95% purity), 18-carat gold is 18 parts gold, 6 parts another metal (forming an alloy with 75% gold), 12-carat gold is 12 parts gold (12 parts another metal), and so forth.[20]

In England, the carat was divisible into four grains, and the grain was divisible into four quarts. For example, a gold alloy of127⁄128fineness (that is, 99.2% purity) could have been described as being23-karat, 3-grain, 1-quart gold.

The carat fractional system is increasingly being complemented or superseded by themillesimalsystem, described above for bullion, though jewelry generally tends to still use the carat system.

Conversion between percentage of pure gold and karats:

  • 58.33–62.50% = 14 c (acclaimed 58.33%)
  • 75.00–79.16% = 18 c (acclaimed 75.00%)
  • 91.66–95.83% = 22 c (acclaimed 91.66%)
  • 95.83–99.95% = 23 c (acclaimed 95.83%)
  • 99.95–100% = 24 c (acclaimed 99.95%)

Volume

[edit]

However, this system of calculation gives only the mass of pure gold contained in an alloy. The term18-carat goldmeans that the alloy's mass consists of 75% of gold and 25% of other metals. The quantity of goldby volumein a less-than-24-carat gold alloy differs according to the alloys used. For example, knowing that standard 18-carat yellow gold consists of 75% gold, 12.5% silver and the remaining 12.5% of copper (all by mass), the volume of pure gold in this alloy will be 60% since gold is much denser than the other metals used: 19.32 g/cm3for gold, 10.49 g/cm3for silver and 8.96 g/cm3for copper.

Etymology

[edit]
Carob (Ceratonia siliqua) pod and seeds, origin ofcaratvia Arabicqīrāṭwhich itself comes from the Greek word for the seedkerátion

Karatis a variant ofcarat.First attested in English in the mid-15th century, the wordcaratcame fromMiddle Frenchcarat,in turn derived either from Italiancaratoor Medieval Latincarratus.These were borrowed into Medieval Europe from theArabicqīrāṭmeaning "fruit of the carob tree", also "weight of 5 grains", (قيراط) and was a unit of mass[21]though it was probably not used to measure gold in classical times.[22]The Arabic term ultimately originates from theGreekkerátion(κεράτιον) meaningcarobseed (literally "small horn" )[22][23][24](diminutive ofκέρας–kéras,"horn"[25]).

In 309AD,Roman EmperorConstantine Ibegan tominta new gold coin, thesolidus,that was1⁄72of alibra(Roman pound) of gold[26]equal to a mass of 24siliquae,where each siliqua (orcarat) was1⁄1728of a libra.[27]This is believed to be the origin of the value of the karat.[28]

Verifying fineness

[edit]

While there are many methods of detecting fake precious metals, there are realistically only two options available for verifying the marked fineness of metal as being reasonably accurate:assayingthe metal (which requires destroying it), or usingX-ray fluorescence(XRF). XRF will measure only the outermost portion of the piece of metal and so may get misled by thick plating.

That becomes a concern because it would be possible for an unscrupulous refiner to produce precious metals bars that are slightly less pure than marked on the bar. A refiner doing $1 billion of business each year that marked.980 pure bars as.999 fine would make about an extra $20 million in profit. In the United States, the actual purity of gold articles must be no more than.003 less than the marked purity (e.g..996 fine for gold marked.999 fine), and the actual purity of silver articles must be no more than.004 less than the marked purity.[29]

Fine weight

[edit]

A piece ofalloymetal containing a precious metal may also have the weight of its precious component referred to as its "fine weight". For example, 1troy ounceof 18 karat gold (which is 750 ‰ gold) may be said to have a fine weight of 0.75 troy ounces.

Most modern government-issued bullion coins specify their fine weight. For example, the American Gold Eagle is embossedOne Oz. Fine Goldand weighs 1.091 troy oz.

Troy mass of silver content

[edit]

Fineness of silver inBritainwas traditionally expressed as themassof silver expressed introy ouncesandpennyweights(1⁄20troy ounce) in onetroy pound(12 troy ounces) of the resulting alloy.Britannia silverhas a fineness of 11 ounces, 10 pennyweights, or aboutsilver, whereassterling silverhas a fineness of 11 ounces, 2 pennyweights, or exactlysilver.

See also

[edit]

References

[edit]
  1. ^London Bullion Market Association."Definitions".Archivedfrom the original on 2015-07-12.
  2. ^Seyd, Ernest (1868).Bullion and foreign exchanges theoretically and practically considered.E. Wilson. p.146.Retrieved21 March2012.
  3. ^"The Perth Mint:: History".Gold Corporation.Archivedfrom the original on 2011-05-14.Retrieved2011-05-08.
  4. ^Thomas, Athol.90 Golden Years, The story of the Perth Mint.Gold Corporation. p. 58.
  5. ^Royal Canadian Mint."The Million Dollar Coin – a true milestone in minting".Archivedfrom the original on 9 March 2015.Retrieved13 July2017.In October 2007, the Million Dollar Coin was certified by Guinness World Records to be the world's largest gold coin.
  6. ^"Fineness of Gold".Gold Rate for Today. Archived fromthe originalon August 7, 2013.Retrieved2013-08-15.
  7. ^"..:: Royal Silver Company::."Archivedfrom the original on 2013-03-16.
  8. ^U.S. Mint abandons 90 percent silver composition
  9. ^"Silver standards".Antiques in Oxford.Retrieved2020-10-05.
  10. ^"1 Rouble, Paul I, Russian Empire".en.numista.com.Retrieved2024-03-22.
  11. ^"1 Rouble, Alexander II-III, Russian Empire".en.numista.com.Retrieved2024-03-22.
  12. ^"Canadian Coin Melt Values - Coinflation".www.coinflation.com.Archivedfrom the original on 2017-06-17.Retrieved2017-11-12.
  13. ^"Decoplata: The History of.720 Silver in World Coinage".18 January 2022.
  14. ^"10 Escudos, Angola".en.numista.com.Retrieved2021-11-04.
  15. ^"10 Sen - Taishō, Japan".en.numista.com.Retrieved2021-11-13.
  16. ^"1 Peso, Uruguay".en.numista.com.Retrieved2021-11-04.
  17. ^Melaragno, Michele.The VNR Dictionary of Engineering Units and Measures.Van Nostrand Reinhold. p. 114.
  18. ^The VNR OXFORD Dictionary for Scientific Writers and Editors.Oxford University Press. p. 56.
  19. ^"United States Code, 16 CFR 23.3 - Misrepresentation as to gold content".Archivedfrom the original on 2017-02-14.
  20. ^Comprehensive Jewelry Precious Metals OverviewArchived2015-02-17 at theWayback MachineInternational Gem Society (IGS), Retrieved 01-16-2015
  21. ^caratArchived2010-10-24 at theWayback Machine,Oxford Dictionaries
  22. ^abHarper, Douglas."carat".Online Etymology Dictionary.
  23. ^κεράτιονArchived2012-10-08 at theWayback Machine,Henry George Liddell, Robert Scott,A Greek-English Lexicon,on Perseus
  24. ^Walter W. Skeat (1888),An Etymological Dictionary of the English Language
  25. ^κέραςArchived2012-10-08 at theWayback Machine,Henry George Liddell, Robert Scott,A Greek-English Lexicon,on Perseus
  26. ^Vagi, David L. (1999).Coinage and History of the Roman Empire.Vol. II: Coinage. Chicago: Fitzroy Dearborn. p. 100.ISBN978-1-57958-316-3.Archivedfrom the original on 7 June 2013.Retrieved18 November2011.
  27. ^Grierson, Philip (1968).Catalogue of the Byzantine Coins in the Dumbarton Oaks Collection and in the Whittemore Collection.Vol. 2: pt. 1. Washington, DC: Dumbarton Oaks. p. 8.ISBN978-0-88402-024-0.Archivedfrom the original on 6 June 2013.Retrieved18 November2011.
  28. ^Turnbull, L. A.; Santamaria, L.; Martorell, T.; Rallo, J.; Hector, A. (2006)."Seed size variability: From carob to carats".Biology Letters.2(3):397–400.doi:10.1098/rsbl.2006.0476.PMC1686184.PMID17148413.
  29. ^"15 U.S. Code Chapter 8 - FALSELY STAMPED GOLD OR SILVER OR GOODS MANUFACTURED THEREFROM".Archivedfrom the original on 2016-11-07.
[edit]
Retrieved from "https://en.wikipedia.org/w/index.php?title=Fineness&oldid=1271159792"