Gold-Filled Calculator

How gold-filled scrap value is calculated

Gold-filled jewelry is not a lump of gold with a little alloy in it. A sheet of gold alloy is bonded to a base metal, and the stamp tells you what share of the weight that sheet is. The calculator uses one line: item weight × ratio × karat ÷ 24. The ratio is the share that is gold alloy. Dividing the karat by 24 turns that alloy into pure gold. A 10 gram piece marked 1/20 14K holds 10 × 1/20 × 14/24, which is 0.292 grams of pure gold. The same 10 grams marked 1/10 14K holds twice that, 0.583 grams, because the layer is twice the share of the weight. The melt line prices only those pure grams. The brass, copper, or other base under the layer is not gold, and it is not in the number.

Weight can be grams, pennyweight, troy ounces, or regular ounces. The math converts to grams first. One pennyweight is 1.555 grams, and one troy ounce is 31.1035 grams. A regular ounce is 28.35 grams and is a different unit. If the stamp gives a ratio this menu does not list, use Custom ratio and type 0.05 or 1/30. A number bigger than 1 is rejected, so typing 20 does not silently become 1/20.

What 14/20 and 1/20 14K mean

Jewelers write the same fact two ways. “1/20 14K” puts the fraction first and the karat second. “14/20” puts the karat first and the fraction’s denominator second. Both mean that one twentieth of the metal weight is 14 karat alloy. They do not mean the piece is 14 parts gold and 20 parts something else, and they do not mean 14 divided by 20. Set the ratio to 1/20 and the layer karat to 14K. The same reading works for 12/20 and 10/20: 1/20 of the weight, in 12K or 10K alloy.

The US Federal Trade Commission Jewelry Guides, 16 CFR 23.3, are the rule behind those marks. A mechanical plating of gold alloy, at least 10 karat, bonded to all significant surfaces, may be called gold filled when that plating is at least 1/20 of the weight of the metal in the whole article. The karat has to sit immediately in front of the words and be just as easy to see, as in “14K Gold Filled” or “14 Kt. G.F.” A bare “14K GF” states the floor, which is 1/20, unless the stamp also prints a thicker fraction such as 1/10. This calculator does not add gold the stamp does not claim.

1/10, 1/20, and 1/40

1/10 and 1/20 are both thick enough for the gold-filled name, provided the layer is at least 10 karat and was applied mechanically. 1/10 is simply a heavier layer: 10 percent of the weight instead of 5 percent. 1/40 is a different name. The same FTC section uses 1/40 as the floor for “gold plate,” “gold overlay,” and “rolled gold plate,” and it asks for the fraction to be shown, as in “1/40 12 Kt. R.G.P.” Calling a 1/40 piece gold-filled would overstate it. The menu still offers 1/40, because that stamp is common, and the note under the menu says it is rolled gold plate or overlay rather than gold filled.

The layer karat is the quality of that sheet only. 14K on the layer is 14 ÷ 24, or 58.3 percent gold. A 585 stamp on the same layer is 58.5 percent. This page prices 14K as 14 ÷ 24, the same way the other calculators on this site do, and it says so next to the result. 12K is 12 ÷ 24, which is 50 percent. 10K is 10 ÷ 24, which is 41.7 percent. Custom purity accepts a percent up to 100, or a fineness such as 585. The karat never describes the whole necklace. Most of the weight is the core.

Gold-filled, plated, vermeil, and solid gold

Solid gold is gold all the way through, alloyed to a karat. A 14K solid band is 14/24 gold in every gram you weigh. Use the karat calculators for that. Gold-filled is a mechanical sheet bonded to a base, thick enough that the FTC puts the floor at 1/20 of the metal weight, and the stamp names the karat of the sheet.

Gold plate and gold electroplate are a film put on by electricity or as a thin mechanical coat. The film is measured in microns, not as a fifth or a twentieth of the weight. Running a plated chain through the 1/20 setting will invent gold that was never there. Vermeil is a different product again. Under 16 CFR 23.4, vermeil is a sterling silver base coated on all significant surfaces with gold, or gold alloy of at least 10 karat, at least 2.5 microns thick. The value is mostly the silver, plus a thin gold coat. This page does not price the silver and should not be used for vermeil.

How to read the stamp

Look on the clasp, the end cap, or inside a locket frame. Useful marks include “1/20 14K GF,” “14K GF,” “14/20,” “1/10 12K GF,” and “1/40 10K RGP.” GF and G.F. mean gold filled. RGP, rolled gold plate, and gold overlay are the thinner family, and they should carry the fraction. A karat number alone, with no fraction and no GF, may be solid gold. HGE means heavy gold electroplate, which is still a plate, not a 1/20 sheet. If the mark is worn off, the color of the metal will not settle it. A refiner can test the piece. Until then, do not pick 1/10 just because the chain looks yellow.

Why the scrap number is small

Take the 10 gram 1/20 14K example again. Only 0.50 grams of that weight is 14K alloy, and only 0.292 grams of it is pure gold. A solid 14K piece of the same 10 grams holds 5.83 grams of pure gold, about twenty times more. Buyers who pay on melt are paying for that small pure-gold figure, then taking a margin. The optional payout box multiplies the melt by a percent you type. It stays off until you turn it on, and this page does not invent the percent. Stones, a steel clasp, and dirt on the scale all sit outside the formula. Weigh the metal the stamp describes.