To calculate the weight of the gold in a scrap gold necklace, first you need to figure out what its gold purity is, and then you can find out how much pure gold you have to value it at current prices.
Figuring Out the Purity of a Scrap Gold Necklace
The term “purity” when used in reference to gold jewelry denotes the proportion of pure gold that it contains relative to the amount of other metals in the gold alloy.
Apart from gold, such alloys contain one or more additional metals such as zinc, silver, copper, and nickel, which make the material harder and more durable.
To find out the purity of a scrap gold necklace, first look closely at it, and see if you can spot any karat marks, such as 10K, 14K, 18K, or 20K.
If you can’t see any karat stamps, you will need to have the necklace tested for purity. Most jewelers can do that for you.
You can also test your scrap gold necklace for karats at home – you will just need to buy a gold testing kit. (Click here to browse through a selection of gold testing kits.)
After you’ve figured out the karat number of the gold necklace, you can convert that value to a percentage. Simply divide the karats by 24 and multiply the result by 100.
For example, a 20-karat gold chain contains 83.3% pure gold (calculated as 20/24 x 100).
If the marks on the chain are not the standard 2-digit numbers but instead have 3 digits, then its purity is most likely expressed as parts per thousand. To convert such a number to a percentage, simply divide by 10.
Thus, a mark that reads “833” means that the chain contains 83.3% gold. The most common parts-per-thousand numbers you are likely to see are 417, 583, 750, 833, and 917.
Determining the Weight of Pure Gold in a Necklace
After you have determined the percentage of gold content in your necklace, you can find out how much pure gold it contains in grams or ounces. All you need to do is weigh the necklace on a precise scale.
Be sure to remove any parts that are not gold so that you don’t include their weight, e.g. pendants made of another material or gemstones.
When you know the weight of the scrap gold necklace, simply multiply that number by the purity of the gold alloy.
As an example, let’s assume that you have a necklace that weighs 10 grams, and you have determined that it is 18 karats pure.
We know that 18 karats translates to 75% gold content, so we can calculate that out of the 10 grams gold alloy the necklace is made of, 7.5 grams is pure gold.
Gold dealers often use troy ounces and pennyweights instead of grams to measure gold. Here is how grams are converted to these units:
1 gram is equal to approximately 0.0322 troy ounces.
1 gram is equal to approximately 0.643 pennyweights (dwt).
1 troy ounce is equal to 20 pennyweights (dwt).
Determining the Value of a Scrap Gold Necklace
Now that you know how much pure gold there is in your necklace, you can estimate its value.
Dealers that buy scrap gold will quote you a price per gram or ounce, and you can look up their quotes on some of their websites to calculate how much you can get for your gold.
Alternatively, you can estimate the value of your scrap gold necklace based on current gold market prices.
You can assume that a gold dealer will pay a price per gram of pure gold that will be about 80% of the price the metal sells for on commodity exchanges.
Where to Buy a Gold Chain?
If you're looking to buy a gold chain, we recommend that you check out the great selection of chains available at Amazon.