There are 31.1035 grams in 1 troy ounce of gold. This is the standard measurement used for precious metals, and is heavier from the avoirdupois ounce (28.3495 grams) used for everyday items.
The value of gold reserves in the top 10 countries holding the largest gold reserves remained stable in recent years. According to World Gold Council, all the gold ever mined is 190,040 tons.