Troy weight them Holland troy, Paris troy, etc. Their values varied from one another by up to several percentage points. Troy weights were first used in England in the 15th century, and were made official for gold and silver in 1527. The British Imperial system of weights and measures (also known as Imperial units) was established in 1824, prior to which the troy weight system was a subset of pre-Imperial English units. The troy ounce in use today is essentially the same as the British Imperial troy ounce (1824–1971), adopted as an official weight standard for United States coinage by Act of
Hong Kong units of measurement and the inch or "tsun" (). Chinese, Imperial and metric weight units are all used in Hong Kong. The choice of system depends on the type of goods and their origins. Metric is used for all official purposes, for example the Post Office and Road signs. Packaged food weights and volumes may be given using any of the three systems of units. Traditional weights are still "de facto" standard in certain areas. For example, vegetables, meats, and Chinese medicines are usually measured in Chinese units, while some fruits are normally measured using the Imperial system. Precious metals (gold, silver and