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Troy weight is a system of units of mass customarily used for precious metals, black powder, and gemstones.

Named after Troyes, France, the troy system of weights was known to exist in medieval times, at the celebrated fair at Troyes in North Eastern France. One cubic inch of distilled water, at 62 °F (17 °C), and at a barometric pressure of 30 inches of mercury, was determined to weigh 252.458 troy grains (gr).^[1]

Troy ounce

The troy ounce (ozt) is 480 grains, somewhat heavier than an avoirdupois ounce (437.5 grains).^[2] A grain is exactly 64.79891 mg; hence one troy ounce is exactly 31.1034768 g, about 10 percent more than the avoirdupois ounce, which is exactly 28.349523125 g. The troy ounce is traditionally used over the avoirdupois ounce in the pricing of precious metals, gold, platinum, and silver. The grain, which is identical in both the troy and avoirdupois systems, is used to measure arrow and arrowhead weights in archery and bullets and powder weights in ballistics. The grain is also common to the apothecaries system and was long used in medicine, but has been largely replaced by milligrams.

Pennyweight dwt

There are 24 grains in 1 dwt, and 20 dwt in one Troy Ounce.

Troy pound

The troy pound (troy) is 5,760 gr (≈ 373.24 g, 12 ozt), while an avoirdupois pound is heavier at 7,000 gr (≈ 453.59 g).

There are 12 troy ounces per troy pound,^[2] rather than 16 avoirdupois ounces (oz) in the avoirdupois pound (lb) as in the more common avoirdupois system. The avoirdupois pound is 14⁷⁄₁₂ (≈ 14.583) troy ounces.

Scottish system

In Scotland the Incorporation of Goldsmiths of the City of Edinburgh used a system in multiples of sixteen. (See Assay-Master's Accounts, 1681-1702, on loan from the Incorporation to the National Archives of Scotland.) Thus there were 16 drops to the troy ounce, 16 ounces to the troy pound, and 16 pounds to the troy stone. The Scots had several other ways of measuring precious metals and gems, but this was the common usage for silver and gold.

Conversions

Unit	Grains	Grams
Troy pound (12 troy ounces)	5,760	373.241 721 6
Troy ounce (20 pennyweights)	480	31.103 476 8
Pennyweight	24	1.555 173 84
Grain	1	0.064 798 91

English pounds
Unit v t e	Pounds											Ounces						Grains		Metric
Unit v t e	Avdp.		Troy		Tower		Merchant		London		Metric	Avdp.		Troy		Tower		Troy	Tower	g	kg
Avoirdupois	1		⁠175/144⁠	= 1.21527	⁠35/27⁠	= 1.296	⁠28/27⁠	= 1.037	⁠35/36⁠	= 0.972	≈ 0.9072	16		⁠14+7/12⁠	= 14.583	⁠15+5/9⁠	= 15.5	7,000	0⁠9,955+5/9⁠	≈ 454	≈ ⁠5/11⁠
Troy	⁠144/175⁠	≈ 0.8229	1		⁠16/15⁠	= 1.06	⁠64/75⁠	= 0.853	⁠4/5⁠	= 0.8	≈ 0.7465	⁠13+29/175⁠	≈ 13.17	12		⁠12+4/5⁠	= 12.8	5,760	08,192	≈ 373	≈ ⁠3/8⁠
Tower	⁠27/35⁠	≈ 0.7714	⁠15/16⁠	= 0.9375	1		⁠4/5⁠	= 0.8	⁠3/4⁠	= 0.75	≈ 0.6998	⁠12+12/35⁠	≈ 12.34	⁠11+1/4⁠	= 11.25	12		5,400	07,680	≈ 350	≈ ⁠7/20⁠
Merchant	⁠27/28⁠	≈ 0.9643	⁠75/64⁠	= 1.171875	⁠5/4⁠	= 1.25	1		⁠15/16⁠	= 0.9375	≈ 0.8748	⁠15+3/7⁠	≈ 15.43	⁠14+1/16⁠	= 14.0625	15		6,750	09,600	≈ 437	≈ ⁠7/16⁠
London	⁠36/35⁠	≈ 1.029	⁠5/4⁠	= 1.25	⁠4/3⁠	= 1.3	⁠16/15⁠	= 1.06	1		≈ 0.9331	⁠16+16/35⁠	≈ 16.46	15		16		7,200	10,240	≈ 467	≈ ⁠7/15⁠
Metric		≈ 1.1023		≈ 1.3396		≈ 1.4289		≈ 1.1431		≈ 1.0717	1		≈ 17.64		≈ 16.08		≈ 17.15	7,716	10,974	= 500	= ⁠1/2⁠

The troy system was used in the Apothecaries' system, but with different further subdivisions.

Relationship to British coinage

The troy system was the basis for the pre-decimalisation British system of coinage introduced by Henry II of England, in which the penny was literally one pennyweight of silver. One pound sterling was equal to twenty shillings, with each shilling equal to twelve pennies. Thus, one pound sterling equals 240 pennyweights, or one troy pound of sterling silver. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.

rayah

SYLLABICATION: ra·yah PRONUNCIATION: räy, r VARIANT FORMS: also ra·ya NOUN: A Christian subject under an Ottoman ruler. ETYMOLOGY: Turkish râya, from Arabic ra‘yah, subject, flock, from ra‘, to pasture, feed. See rcy in Appendix II.

CONTENTS · INDEX · ILLUSTRATIONS · BIBLIOGRAPHIC RECORD

  Ray, Satyajit Rayburn, Samuel  www.ASHTON.com www.summerfairolympia.com www.IKEA.com

≈preface:₨ RN MR Roy Newymann Noorman. Lyndtt Barker Yanne. Aldersbrook -Frabrizio-Green Enfield (Ferreli-Merccedes-Corp) MICHAELIN TYRE TYPE series F-12 1884-1994. Ad. Resident. rite FRANCAIS-ANGLAIS, COLLINS HEWITT-STUART Pi CK A RD2 modal Kelvin, Engel, Nigella, French C. Circle Epoch. cantioch. vault sepluchral meosoteric. NIV IV44 (King Edward' Holy-Bilble Ruebens-Ruby Red edition) Bella Norway.₨ Dr, Irving, Boyle Scott Tayler/ BERKSHIRE St.Johns ISLINGTON. Miss O' mara Laslye Aunton Resident. rite. National Surname. Francois Henry Cranbury Felten. Caledonia Miller-Patterson CPW co-worker. Hudson Bay, Pella, Canary Wharf, Liverpool Dockstreet (Dublin~O' Ara Aston-Rayah Yan)-Edinburgh (PUK-ICS-COI) 285952 1p 4m Mar08. England or Wales. ₨ Davis Arroyen/Jensen. Bassett. Margott. Mr Andrew Jeremy Ashton. Tate-Tyne and Belfast.//Joanne Aubray Ryanner, Edinburgh and Tunbridge, Elles. .Greayhm, Thompkinson, Bray Margaret. Carat. CATERPILLER. COMPANY ADV WI-FI.//Anne-Mary Edmon/Ampere. Asher-Naylor. Edinburgh Malboro Crescent. .Invik SA Inter-Matalan, Newcastle-Upon-Tyne Belfast, Dublin, Norway-Ireland 0871 231 9023 Berkshire, York, Newport. Luxembourg.

References

^ Wightman, S. (1840). Wightman's Arithmetical Tables. Westminster: S. Wightman. OCLC 43196919. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b "Troy Ounce". WordNet 3.0, Dictionary.com. Princeton University. Retrieved 2008-01-10.

[1] Wightman, S. (1840). Wightman's Arithmetical Tables. Westminster: S. Wightman. OCLC 43196919. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[dictionary.com-2] "Troy Ounce". WordNet 3.0, Dictionary.com. Princeton University. Retrieved 2008-01-10.

[1]

[2]