Troy Ounce
The troy ounce is the basic unit of weight used to measure gold.
1 troy ounce (t oz or oz t) = 31.1034 grams (g)
1 pennyweight (dwt) = 1.5552 grams (g)
1 troy ounce (t oz or oz t) = 480 grains (gr)
(Be careful as the everyday U.S. “avoirdupois” ounce is only 28.3495 grams!)
24K = 100% (99.9% or better)
22K = .916 or 91.6%
18K = .75 or 75%
16K = .666 or 66.6%
14K = .583 or 58.3%
10K = .416 or 41.6%
8K = .333 or 33.3%
Check the purity you sell to your silver buyer:
Investment Grade Fine = 99.9% pure or .999 or “three nines fine”
Sterling Silver = 92.5% pure, marked 925
Show your platinum buyer these marks:
950 Platinum = 95% marked 950 Pt / 950 / PLT / PLAT / PLATINUM
900 Platinum = 90% marked 900 Pt
850 Platinum = 80% marked 800 Pt