Gold Value Calculator

How the Calculation Works

The arithmetic is simple, and worth understanding so you can sanity-check any figure a buyer quotes you:

value = weight × purity × spot price

Weight is the mass of the item. Purity, or fineness, is the proportion of that mass which is actually gold. Spot price is the market price of one troy ounce of pure gold, which moves continuously while markets are open.

Karat states purity as parts per twenty-four:

A 10-gram 18K ring therefore contains 7.5 grams of gold, not 10. That step is the one most people miss, and it is why a jewellery valuation so often disappoints.

Troy Ounces, Grams and Pennyweight

Precious metals are priced in troy ounces, not the avoirdupois ounces used for groceries. One troy ounce is 31.1034768 grams — roughly 10 per cent heavier than the ordinary ounce of about 28.35 grams. Confusing the two overstates a holding by about a tenth.

Pennyweight (dwt) is still used in the jewellery trade, particularly in the United States. One pennyweight is one twentieth of a troy ounce, or about 1.5552 grams. A buyer quoting per pennyweight is not doing anything improper, but the number looks larger than a per-gram quote for the same metal — convert before you compare.

Why a Buyer Will Not Pay You This Number

The figure above is intrinsic metal value at spot. It is a ceiling, not an offer.

• Refining. Scrap gold must be melted and assayed before the metal re-enters the market. That costs money, and it comes out of your price.
• Dealer margin. The buyer is running a business and carries price risk between buying from you and selling on.
• Assay uncertainty. Where purity is not certain, a buyer prices conservatively.
• Form. Recognised bullion — a hallmarked bar, a widely traded coin — sells closest to spot. Broken jewellery sells furthest from it.

Offers for scrap jewellery sit materially below spot and vary a great deal between buyers. Getting more than one quote is the single most effective thing you can do, and only quotes taken on the same day are comparable.

Reading a Hallmark

Gold sold in the UK, the EU and much of the Commonwealth usually carries a stamped fineness — 375, 585, 750, 916, 999 — often alongside an assay office mark. Goods made for the US market are more often marked in karats: 10K, 14K, 18K.

A mark is evidence, not proof. Unmarked, worn or plated items need testing. Acid testing removes a trace of metal; XRF analysis does not, and any established buyer should have it.

Gold-filled, rolled gold and gold-plated are not gold items. Plating is measured in microns, and its recoverable metal value is generally negligible.

What This Calculator Does Not Account For

• Gemstones, pearls and non-gold settings — excluded from metal weight, but included on your scale.
• Clasps, springs and pins, which are frequently a lower fineness than the body of the piece.
• Numismatic or collectible premium. Some coins are worth considerably more than their metal, and melting one destroys that value permanently. Check before selling any dated coin.
• Designer or brand premium on finished jewellery.
• Dealer premiums over spot, which apply when you are buying rather than selling.
• Tax. Treatment of precious metals varies by jurisdiction, and by whether an item is investment-grade bullion or jewellery. Check your own position before you transact.

Weighing Accurately

Use a scale reading to 0.1 g or better, and weigh each fineness separately — mixing 9K and 18K into a single figure produces a number that is wrong for both. Remove stones where they come out, and weigh chains without their tags.