Read the complete mark
A fineness number such as 925 is a statement about silver content, but a number stamped on an object is not automatically an independent assay. In the UK system, a complete hallmark includes a sponsor's mark, a fineness mark and an assay-office mark. Government guidance explains that the hallmark records independent testing against the relevant purity standard. This is a specific national framework, not a universal stamp format.
Match the object to its records
Read the invoice, product specification and recognised issuer or refiner details alongside the physical item. Weight, dimensions, packaging and identifying marks provide useful points of comparison with the manufacturer's specification. None should be interpreted in isolation as a guarantee. A discrepancy is a reason to investigate, rather than to improvise a destructive test on a valuable or collectible object.
Know what the instrument sees
X-ray fluorescence, or XRF, examines elemental composition near a material's surface. LBMA explains that this makes it useful for rapid assessment but limits what a reading says about the bulk of an item. A surface result is not automatically a full-depth analysis. Professional testing methods are selected to suit the material, its form and the level of assurance required.
Purity is one question among several
An assay concerns composition. It does not, by itself, settle legal ownership, provenance, collectible rarity or what a buyer will offer. Those are separate enquiries supported by different records and expertise. For an unfamiliar purchase or a disputed item, the practical next step is a reputable dealer, recognised assay office or appropriately equipped professional. Preserve the documentation and distinguish verified facts from assumptions before valuing the item. A useful report names the method, describes the sample and states the result clearly. Keeping those details with the item makes the evidence more meaningful than a reassuring verbal claim that it has simply been checked.
Sources & further reading
Sources checked 14 November 2026. Reference organisations do not endorse this website. Price examples are hypothetical and educational.