How Gold Buyers Test and Weigh Your Jewellery (And How to Make Sure It's Fair)

Every gold purchase comes down to two measurements: how pure the metal is, and how much of it there is. Everything else is commentary. Here is exactly how each measurement is taken, and what a fair process looks like from your side of the counter.

Measurement one: purity

Visual inspection

The evaluation starts with a loupe. The buyer looks for karat stamps, fineness marks, maker's marks and hallmarks, plus signs that a piece is plated — wear points where a base metal shows through, or a colour difference at the edges.

Acid testing on a stone

The classic method, still the workhorse of the trade. The piece is rubbed on a black testing stone to leave a small streak of metal. Graded acid solutions are applied to that streak. A 14k acid will dissolve a 10k streak but leave a 14k streak intact; an 18k acid will dissolve the 14k streak, and so on. The point at which the streak survives identifies the karat.

It is quick, it costs almost nothing, and it leaves a mark so small it is invisible once the piece is cleaned. On heavier items a test may be repeated at more than one point, since clasps and findings are sometimes a different karat than the body.

XRF analysis

X-ray fluorescence analysers read the elemental composition of a surface without damaging it. They are fast and precise for surface composition, but they read the surface — which is why plated items can fool an XRF that is used carelessly, and why a good buyer still cross-checks.

Measurement two: weight

Gold is bought by weight, normally in grams. Some shops quote in pennyweight (dwt), where one pennyweight equals 1.555 grams, or in troy ounces, where one troy ounce equals 31.1 grams. None of these units is dishonest by itself — but if a buyer quotes in a unit you do not use daily, ask them to restate it in grams so you can compare.

Karat sorting comes first

Before anything is weighed, items must be grouped by tested karat. A pile containing 10k, 14k and 22k pieces cannot produce one meaningful number. Sorting is the step where most of the fairness lives.

Deductions for non-gold parts

Stones, spring mechanisms, watch movements and steel pins are not gold and are accounted for. This is legitimate. What is not legitimate is a vague, unexplained deduction. Ask what is being removed from the weight and why.

Four things to watch at the counter

1. Your items never leave your sight. There is no reason for gold to go into a back room.
2. The scale display faces you, or you are shown each reading. Ask if it does not.
3. Items are grouped by karat before weighing, and you can see which group is which.
4. Every deduction is named out loud — stones, clasps, non-gold components.

Questions worth asking

• What karat did each piece test at?
• What is the total weight for each karat group, in grams?
• Are there any fees, testing charges or refining deductions?
• Is this offer good if I come back tomorrow?

A buyer who answers all four plainly is a buyer worth dealing with. A buyer who deflects any of them is telling you something.

How we do it at AGN

Every test and every weighing at AGN happens on the counter between you and us, at 1646 Victoria Park Avenue in North York. We sort by karat, we say each reading out loud, we name every deduction, and we do not charge for any of it. There is no obligation to sell and no time limit on your decision. Call (416) 551-6400 or walk in Monday to Friday 12pm to 7pm, Saturday 12pm to 5pm.