1. Divide the troy ounce gold price by 31.1 (there are 31.1 grams in 1 troy ounce). The price at time of writing is $1386 per ounce, so the value of 1 gram of 24k is $44.56.
2. Now multiply the value per gram by the number of grams of gold that you have for the first pile. So, if you have 12 grams of 9ct then you are left with $534.72. Write down the figure.
3. Now multiply the weight of gold by the number of carats and divide by 24. You have 12 grams of 9ct gold, so multiply 12 grams by 9 and then divide by 24. So basically (12 x 9)/24. In this scenario your scrap gold contains 4.5 grams of scrap gold.
4. You already know the value of 1 gram of pure gold, in this hypothetical scenario it is $44.56; multiply this figure by the quantity of pure gold that you have (44.56 x 4.5). Your 12 grams of scrap 9ct jewelry contains pure gold worth $200.52.
5. Now repeat steps 2, 3 and 4 for all of the gold types that you have. If you have any gold which does not state the gold purity on the hallmark, for example if the hallmark has worn down or it is very old gold which was often unstamped, then you need to take it to a Jeweller to ascertain purity before valuing. Simply add up the value of each of your piles of scrap gold and find the total figure, you now have your gold value. You aren’t going to get this price though when selling scrap, read the next paragraph for an idea of how much you should expect to be paid for the gold.
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http://ryankett.hubpages.com/hub/How-To-Calculate-The-Value-Of-Scrap-Gold
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