troy weight
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troy weight is a historical system of units for measuring mass used primarily for precious metals, gemstones, and coinage. It originated in medieval trade networks and later became standardized in several European and Commonwealth jurisdictions, influencing modern bullion markets, banking houses, royal mints, and assay offices. The system is closely associated with markets, institutions, and people involved in metallurgy, finance, and exploration.
History
The origins trace to medieval trade centers such as Troyes, Venice, Genoa, Cairo and Constantinople where merchants like the Hanseatic League and the Merchant Adventurers exchanged coined silver from rulers including Edward I of England, Philip IV of France, and Charlemagne. During the Late Middle Ages and the Renaissance, merchants operating from Antwerp, Lisbon, Hamburg, and Marseille adopted weight standards to value silver and gold in transactions conducted by entities such as the Knights Templar, Medici family, and Fugger family. The Tudor and Stuart monarchs, including Henry VIII and Elizabeth I, oversaw mints at Tower of London and reforms that interacted with standards used by the Bank of England and later by the Royal Mint. International treaties and conferences such as the Congress of Vienna and conventions among colonial administrations influenced the spread of uniform measures into the British Empire, Spanish Empire, and trading posts controlled by Dutch East India Company and British East India Company.
Units and subdivisions
The system’s primary denominations have long been used in transactions handled by goldsmiths, assayers, and bullion dealers in centers like Zurich, Basel, New York City, and Hong Kong. Subdivisions historically used by craftsmen and merchants often mirror practices found in guilds and institutions such as the Worshipful Company of Goldsmiths and assay offices in London, Paris, and Vienna. Terms and names employed across eras appear in records from the British Museum, archives of the Vatican, and municipal registries in Florence and Prague.
Standards and definitions
Legal and technical standards were established progressively by bodies including the Royal Society, national scientific academies such as the Académie des Sciences, and standards institutes like the National Institute of Standards and Technology and the International Organization for Standardization. Definitions were influenced by metallurgists, assay masters, and economists including figures linked to Isaac Newton at the Royal Mint and financial policymakers in the Bank of England and Federal Reserve System. Treaties, statutes, and regulations from parliaments and congresses, including acts debated in the Parliament of the United Kingdom, the United States Congress, and national legislatures across Europe and Asia, codified specific mass relations used in commerce and coinage.
Usage in precious metals and gemstones
Jewelers, bullion traders, and auction houses such as Sotheby's, Christie's, and commodity exchanges including the London Bullion Market Association and the New York Mercantile Exchange rely on traditional denominations when grading and pricing items by assay reports from laboratories akin to those at Bureau Veritas and national assay offices. The system remains central in valuation practices performed by firms like Goldman Sachs, J.P. Morgan, and refining houses including PAMP Suisse and Valcambi. Gemological institutions and museums such as the Gemological Institute of America, the Smithsonian Institution, and the Victoria and Albert Museum document uses in cataloging diamonds, rubies, sapphires, and historical coins and artifacts.
Conversion and equivalence
Commercial conversions between this system and other units are used by banks, mints, and markets in cities like London, Zurich, Chicago, and Tokyo; conversion tables appear in manuals produced by central banks and commodity exchanges including the London Metal Exchange and Chicago Mercantile Exchange. Accountants, auditors, and brokers at firms such as Ernst & Young, Deloitte, and KPMG apply exact numerical relations in reporting and settlements, while standards bodies like the International Bureau of Weights and Measures influence international equivalence practices.
Comparison with other weight systems
Comparative studies undertaken by universities including Oxford University, Harvard University, University of Cambridge, and University of Paris contrast it with systems historically used in regions administered by the Ottoman Empire, the Mughal Empire, and East Asian polities such as Ming dynasty and Tokugawa shogunate authorities. The system’s interaction with metrication campaigns led by parties in the French Revolution and later institutionalized by the International System of Units provides context for shifts in legal metrology debated in forums like the League of Nations and the United Nations.
Modern legal and commercial status
Contemporary legal frameworks in jurisdictions including the United Kingdom, the United States, Canada, Australia, and member states of the European Union retain statutory references and commercial practice for precious metal trade, overseen by regulators such as national financial authorities and customs agencies linked to ministries in Westminster, Washington, D.C., and Canberra. Market infrastructure participants—banks, exchanges, and clearing houses including the London Clearing House and major bullion banks—continue to price, settle, and insure precious metal transactions referencing this system alongside metric measures. See also institutional archives at the Royal Mint Museum, the British Library, and national museums for historical documentation.