How much gold is in an 1 toz 24k item?

24-karat gold is at least 99.9% pure gold, so 1 troy ounce of 24K gold should have at least 0.999 troy ounces (31.072 grams) of gold.

(Note that the troy ounce, used for precious metals, is slightly larger than the avoirdupois ounce, used for most ordinary measurements. However, a troy pound is 12 troy ounces, instead of 16 ounces as with an avoirdupois pound.)