Pennyweight is derived from the price for a hundred nails in 15th century England: the larger the nail, the higher the cost per hundred. The pennyweight also bears no relation to the weight of the American "penny" (1 cent) coin, which weighs 2.5 g (for those minted after 1982). Pennyweight A pennyweight (abbreviated dwt, from denarius weight) is a unit of mass that is equal to 24 grains, of a troy ounce, 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, of an ounce
Actual silver weight $15.00 per troy ounce, the intrinsic value of a pre-1965 Roosevelt dime would be: 0.072339075 × 15.00 = $1.085086125 ≈ $1.09. (Note that coin stores, pawn shops, and bullion retailers will not necessarily purchase coins from consumers at the intrinsic value because of the costs involved with selling such coins to companies that melt the coins, separate the constituent metals, and prepare the silver for resale.) Actual silver weight Actual silver weight, usually abbreviated ASW, refers to the weight of pure silver contained in a coin, measured in troy ounces. Coin collectors, individuals who invest in bullion coins, and others