How to Weigh Gold and Silver Accurately

Short answer: use a jeweler's scale that reads to 0.01 gram, check it with a known test weight, weigh each piece on its own without packaging, and write the result in grams. A scale that is off by 0.1 g changes the value of a 10 g gold piece by about one percent.

Pick the right scale

Kitchen scales usually read to 1 gram, which is far too coarse for small gold pieces. A pocket jeweler's scale that reads to 0.01 g is inexpensive and enough for coins, small bars and jewelry. Larger silver bars can be weighed on a scale that reads to 0.1 g, as long as it has enough capacity.

Check it before you trust it

Place a calibration weight on the scale and confirm the reading. Many scales come with a 100 g or 200 g weight. If you do not have one, a sealed one-ounce coin from a major mint is a reasonable cross-check, because its fine weight is 31.1035 g, although the coin itself may weigh slightly more or less within the mint's tolerance.

Weigh it properly

• Use a flat, stable surface away from drafts, which move light scales.
• Let the scale warm up and zero it before each piece.
• Weigh the piece out of capsules, holders and sleeves, which add weight.
• Weigh twice and record the average.

Record the unit you will use

Scales usually show grams. Metal prices are quoted per troy ounce, and one troy ounce is 31.1035 grams. Keep your records in grams and convert when you need to, using the gram to troy ounce converter.

Why a small error matters

Melt value is weight times purity times the spot price, so a weighing error passes straight through. If you use the gold melt value calculator with a weight that is 1% too high, the value is 1% too high. Accurate weights also let you spot a counterfeit, which is often light or the wrong size for its weight.