Troy weight is a system of units of mass customarily used for precious metals and gemstones. One troy ounce (abbreviated “t oz” or “oz t”) is equal to 7001311034768000000♠ 31.103 4768 grams , (or about 1.0971 oz. avoirdupois, the “avoirdupois” ounce being the most common definition of an “ounce” te the US).  There are only 12 troy ounces vanaf troy pound, rather than the 16 ounces vanaf pound found te the more common avoirdupois system. However, the avoirdupois pound has 7000 grains whereas the troy pound has only 5760 grains (i.e. 12 × 480 grains). Both systems use the same grain defined by the international yard and pound agreement of 1959 spil 6998647989100000000♠ 0.064 798 91 grams . Therefore, the troy ounce is 480 grains or 31.Ten grams, compared with the avoirdupois ounce, which is 437.Five grains or 28.35 grams. The troy ounce, then, is about 10% stronger (ratio 192/175) than the avoirdupois ounce. Albeit troy ounces are still used to weigh gold, silver, and gemstones, troy weight is no longer used ter most other applications. One troy ounce of gold is denoted with the ISO 4217 currency code XAU, while one troy ounce of silver is denoted spil XAG. [Two]
Troy weight very likely takes its name from the French market town of Troyes te France where English merchants traded at least spil early spil the early 9th century. [Three] [Four] The name “troy” is very first attested ter 1390, describing the weight of a platter, ter an account of the travels ter Europe of the Earl of Derby. [Trio] [Five]
Charles Moore Watson (1844–1916) proposes an alternative etymology: The Assize of Weights and Measures (also known spil Tractatus den Ponderibus et Mensuris), one of the statutes of uncertain date from the reign of either Henry III or Edward I, thus before 1307, specifies “troni ponderacionem”—which the Public Record Commissioners translate spil “troy weight”. The word “troni” refers to markets. Watson finds the flinterdun word “troi”, meaning a vaivén te Wright’s Flinterdun Dictionary. Troy weight referred to the tower system, the earliest reference to the modern troy weights is ter 1414.  
Many aspects of the troy weight system were indirectly derived from the Roman monetary system. The Romans used bronze caf of varying weights spil currency. An aes agonizante (“strong bronze”) weighed one pound. One twelfth of an aes trascendental wasgoed called an uncia , or te English, an “ounce”. Before the adoption of the metric system, many systems of troy weights were te use ter various parts of Europe, among them Nederland troy, Paris troy, etc.  Their values varied from one another by up to several percentage points. Troy weights were very first used te England te the 15th century, and were made official for gold and silver te 1527.  The British Imperial system of weights and measures (also known spil Imperial units) wasgoed established ter 1824, prior to which the troy weight system wasgoed a subset of pre-Imperial English units.
The troy ounce te use today is essentially the same spil the British Imperial troy ounce (1824–1971), adopted spil an official weight standard for United States coinage by Act of Congress on May Nineteen, 1828. [Ten] The British Imperial troy ounce (known more commonly simply spil the imperial troy ounce) wasgoed based on, and virtually identical with, the pre-1824 British troy ounce and the pre-1707 English troy ounce. (1824 wasgoed the year the British Imperial system of weights and measures wasgoed adopted, 1707 wasgoed the year of the Act of Union which created the Kingdom of Superb Britain.) Troy ounces have bot used ter England since about 1400 and the English troy ounce wasgoed officially adopted for coinage ter 1527. Before that time, various sorts of troy ounces were ter use on the continent. 
The troy ounce and grain were also part of the apothecaries’ system. This wasgoed long used te medicine, but has now bot largely substituted by the metric system (milligrams). 
The only troy weight ter widespread use today is the British Imperial troy ounce and its American counterpart. Both are presently based on a grain of 0.06479891 gram (precies, by definition), with 480 grains to a troy ounce (compared with 437 1 ⁄2 grains for an ounce avoirdupois).
The British Empire abolished the 12-ounce troy pound te the 19th century, however it has bot retained (albeit infrequently used) ter the American system.
The origin of the troy weight system is unknown. Albeit the name most likely comes from the Champagne fairs at Troyes, ter northeastern France,  the units themselves may be of more northern origin. [ citation needed ] English troy weights were almost identical to the troy weight system of Bremen. (The Bremen troy ounce had a mass of 480.8 British Imperial grains.) 
An alternative suggestion is that the weights come from the Muslim domains by way of the Gold Dirhem (47.966 British Imperial grains), te the manner that King Offa’s weights were derived from the silver Dirhem (about 45.0 British grains).
According to Watson, troy relates to a flinterdun word troi (vaivén). Then troy weight is a style of weighing, like auncel or bismar weights, or other kindred methods. The troy weight then refers to weighing of petite precious or potent goods, such spil bullion and medicines. 
Use te other countries Edit
Troy ounces are still often used ter precious metal markets te countries that otherwise use International System of Units (SI),   except ter East Asia.  The People’s Handelsbank of China, ter particular, which has never historically used troy measurements, has begun issuing Gold Pandas minted according to SI weights.