Dollar gold to silver ratio be exactly 15.5. Then a pennyweight of gold, that is 24 grains of gold, is nearly equal in value to a dollar of silver (1 dwt of gold = $1.002 of silver). Second, a dollar of gold is nearly equal in value to a pound of silver ($1 of gold = 5754 3/8 grains of silver = 0.999 Lb of silver). Third, the number of grains in a dollar (371.25) roughly equals the number of grams in a troy pound (373.24). The actual process of defining the US silver dollar had nothing to do with any
Troy weight by the international yard and pound agreement of 1959 as . Therefore, the troy ounce is , compared with the avoirdupois ounce, which is 437.5 grains or approximately 28.35 grams. The troy ounce, then, is about 10% heavier (ratio 192/175) than the avoirdupois ounce. Although troy ounces are still used to weigh gold, silver, and gemstones, troy weight is no longer used in most other applications. One troy ounce of gold is denoted with the ISO 4217 currency code XAU, while one troy ounce of silver is denoted as XAG. Troy weight probably takes its name from the French market