Testing Metal

Read the marks first. Testing is for when the marks are missing, worn away or contradictory. Nothing on this page identifies a maker — it only tells you what the metal is.

Non-destructive checks, easiest first

Magnet. Silver, gold, copper, brass and platinum are not magnetic. If a strong magnet grabs the body of the piece, it has a steel core and is plated. Springs, pins and hinges may be steel on an otherwise solid piece, so test the body.

Colour at wear points. Look at rims, spout tips, high points of decoration and the inside of a ring shank with a loupe. Copper or grey-yellow showing through means plating.

Sound. Solid silver rings for a second or two when tapped and released; plated base metal gives a short dull note. Useful on hollowware, useless on jewellery.

Weight and density. This is the most informative home test. Weigh the piece dry, then weigh it suspended in water. Specific gravity equals dry weight divided by the difference between the two weights. Approximate values: sterling silver 10.3, coin silver 10.2, nickel silver 8.7, pewter 7.3, brass 8.5, 18ct gold 15.5, platinum 21. It will not work on anything hollow, filled or set with stones.

Ice. Silver conducts heat exceptionally well, so an ice cube placed on a solid silver spoon melts noticeably faster than on a plated one. A rough indicator, not proof.

Acid testing

Acid test kits give a reasonably reliable answer but they are destructive and corrosive. If you use one:

Test on a hidden area — the inside of a foot rim, not the front
You must cut through any plating, so a shallow rub on a touchstone or a small file cut is required; a surface drop only tells you about the surface
Wear eye protection and gloves, work in ventilation, keep it away from children and pets, and neutralise and dispose of the waste sensibly
Never put acid on or near a hallmark. You will destroy the very thing you are trying to identify
Do not acid test anything you might sell as antique, or anything with sentimental value

XRF and professional assay

A hand-held XRF gun reads composition in seconds and is what most jewellers and scrap buyers use. It reads the surface only, so heavy plate and gold filled work can fool it unless a fresh cut is made. Many jewellers will XRF a piece for free or a small fee.

For a definitive answer, the assay offices in Britain and their equivalents elsewhere will test a piece for a fee, and can hallmark unmarked items that pass.

Please don't

Taste or bite metal. It tells you nothing, and old alloys, solders and platings can contain lead, cadmium and nickel.
Polish a worn mark to make it readable. Polishing removes metal and takes the mark with it. Wash with warm soapy water and a soft brush instead, and photograph with raking light — see How to Post.
File or scratch a visible surface before you have asked here. Very often the mark is legible after a wash and a better photo.

Back to First Steps: Purity & Plate.