The most reliable way to determine whether or not jewelry is platinum it to take it to a certified refiner. Refiners have access to a non-destructive technology to identify elements and determine concentrations of elements present in metal items. Often times refiners will provide free quotes on this service when contacted.
One way to get an accurate answer without a refiner is checking the assay marking. This may require a magnifying glass or jeweler’s loupe. The most common assay markings and purity levels for platinum are:
- Plat (Varying purity)
- Pt (Varying purity)
- 880 (88 percent pure)
- 900 PLAT (90 percent pure)
- 950 PLAT (95 percent pure)
- 10% IRID 90 percent PLAT (90 percent pure, with 10 percent iridium)
On a ring, the assay marking will be stamped on the inside, along the shank. If an assay marking isn't present, a refiner will be necessary to determine the element and purity.