It’s very important to know some basic weight terms if you want to understand charts and discussions and news reports about precious metals and gemstones. Therefore, I’ve provided for you a concise glossary of terms below: avoirdupois ounce, troy ounce, grain, and pennyweight.
NOTE: While most of the world uses the metric system, the United States primarily uses the U.S. customary system (also called the American system) to measure weight.
Avoirdupois ounce is abbreviated oz.
1 avoirdupois ounce = .911458333 troy ounces, 437.5 grains or 28.349523125 grams
Definition of Troy Ounce
Gemstones and precious metals such as gold, silver, and platinum are sold by the troy ounce. It is heavier than the avoirdupois ounce.
Definition of Grain
A grain is a unit of weight in both the U.S. customary system and the troy system that weighs the same under both systems. Its abbreviation is gr.
1 unit of grain = 0.002285 ounces or 0.06479891 grams
Definition of Pennyweight
Jewelers use the pennyweight in calculating the amount and cost of precious metals used in fabricating or casting jewelry. Dentists still use the pennyweight as the measure of precious metals in dental crowns and inlays. It has no relation to penny coins.
Well, I hope you found this introduction helpful! Let me know if you enjoyed this information or if there is something I can add to it to make it easier to understand or better in any way. Thanks!