*** Welcome to piglix ***

Pennyweight


A pennyweight (abbreviated dwt or denarius weight) is a unit of mass that is equal to 24 grains, 120 of a troy ounce, 1240 of a troy pound, approximately 0.054857 avoirdupois ounce and exactly 1.55517384 grams.

In the Middle Ages, a British penny's weight was literally, as well as monetarily, 120 of an ounce and 1240 of a pound of sterling silver. At that time, the pound in use was the Tower pound (5,400 troy grains). The medieval English pennyweight was thus equal to 32 Tower grains (also known as wheat grains). When Troy weights replaced Tower weights in 1527, the Troy weights were defined in such a way that the old Tower pound came out to exactly 5400 Troy grains (also known as barleycorns), the Tower pennyweight 22 12 Troy grains (and thus approximately 1.46 grams). After 1527, the English pennyweight was the Troy pennyweight.

The Troy pound and the pennyweight lost their official status in the United Kingdom in the Weights and Measures Act of 1878; only the Troy ounce and its decimal subdivisions remained official. The Troy ounce enjoys a specific legal exemption from metrication in the UK.

The pennyweight is the common weight used in the valuation and measurement of precious metals. Jewellers use the pennyweight in calculating the amount and cost of precious metals used in fabricating or casting jewellery. Similarly, dentists and dental labs still use the pennyweight as the measure of precious metals in dental crowns and inlays.


...
Wikipedia

...