Popular coins and small bars with famous stamps are copied. The first filter is a counterparty you can still find in a year, and a check of weight and dimensions against a published figure. That is a filter for the obvious. It is not a home laboratory, not a guarantee, and not a test manual.
A filter, not a laboratory
A filter asks whether this object fails an obvious check against a known spec or a known desk. A laboratory asks whether the metal is what the stamp claims, to a stated tolerance, under a method that can damage a good piece if it is done badly.
A piece that matches weight and dimensions can still be plated, filled, or struck from the wrong alloy. A piece that fails them is a reason to stop treating the stamp as settled. The gap between those two facts is why a filter is not a guarantee.
Counterparty before gadgets
The first defence is the desk, not the scale. A counterparty you can still find in a year has a name, a place, and a history that can be checked without their own FAQ. They will still answer after the parcel arrives. A stranger at a table, a social-media account, or a one-week shopfront has none of that.
A widely struck government coin or a well-known small bar has a published weight, a published diameter, and a public vocabulary of usual copies. An obscure commemorative, or a private pour with no serial, has fewer figures to check against. Popularity also attracts copies. A common type is easier to filter and easier to fake.
Metal that has already been accepted still has to sit somewhere — home, an allocated vault, or an unallocated claim. That menu is storing gold and silver. Whose books you trusted, and whether the object matches the spec, comes before the place it sits.
Weight, dimensions, edge, reed, stamp
Weight is the cheapest published number. Mints and refiners print a troy weight and a tolerance. A scale that resolves a tenth of a gram will show a piece that is light or heavy against that figure. A piece far off is not yet proven fake. It is no longer a piece you treat as settled on the stamp alone.
Diameter, thickness, and sometimes a shape come next. A minted coin is a repeatable object. A poured bar is less so, but a famous small bar still has a length and a width in a public spec. Right weight and wrong size means a different alloy or a different object. Together the two checks only remove the crude copies.
Reeding that is uneven, a stamp that is soft or crowded, a colour that is trying too hard — compare those against a known genuine piece of the same product if one is at hand. Colour is the weakest of the four. Lighting and wear change it. None of the looks is conclusive.
A price far below the field
A quote far below everyone else’s print is information. Spot is a screen price for a paper ounce. The object on a counter carries fabrication, shipping, and a dealer’s book. An ask that undercuts that whole field by a wide margin has to be explained by something other than generosity — a distressed sale, a thin market, or a stamp that is not the metal.
Treat the outlier as a warning, not a bargain. A high ask is not proof of honesty. A low ask is not proof of a fake. The price is one more reason to stop.
When a professional is needed
Weight and a ruler do not close a case where a fake would change a household’s or a firm’s books. A desk that will still be there next year does not close it either, if the object itself is the question.
Assay offices, refiners, and some dealers run the tests that settle a doubtful piece. Sending a piece out costs time and a fee. Keeping a doubtful piece without that step leaves the risk that the stamp is theatre. If a plated bar or a filled coin would matter, use a professional.
Kitchen tests
Acid tests, X-ray fluorescence, ultrasound, specific-gravity baths, and magnet tricks are not a home method. A wrong test can damage a good piece. A right test, done without a method, can still be misread. Popular coins and famous small bars attract copies that already know the amateur checks.