The reference data, as data

What is in it

• 26 hallmarks — the stamp, what it asserts in parts per thousand, which metal it is about, and where in the world you meet it.
• 7 layered-gold marks — gold filled and gold plated, with the fraction of total weight where the standard defines one.
• 20 coin specifications — gross weight, fineness, years, and the silver content derived from them.
• 23 ring sizes — US, UK, EU and Japanese scales against the inside diameter and circumference in millimetres.
• 14 metal densities, and the six weight units precious metals are actually traded in.

Why publish it

Hallmark tables and ring-size charts are among the most copied reference data on the web, and most copies are scrapes of scrapes: undated, unattributed, and subtly wrong. 14K appears as 585 in one table and 583 in another with no explanation of why both are correct. Gold-plated marks get given a gold content they do not state. If somebody is going to copy this data anyway, it may as well be a version that says what it is.

Read this before using it

• A hallmark is a nominal claim about purity, not a measurement of it. A stamp tells you what the maker asserted; only an assay tells you what the metal is.
• Where a legal standard and plain division disagree, this data follows the stamp. 14K is 583.3 by division and is stamped 583 in the US or 585 in Europe — both appear, and neither is an error.
• Gold-PLATED marks state no quantity at all, so their gold content is null rather than zero or a guess. Only gold-FILLED marks define a fraction of total weight.
• Alloy densities are ranges because composition varies between makers. A single density for an alloy is a fiction; the range is the honest form.
• Coin silver and gold content is DERIVED from published gross weight and fineness, not copied from a table. Circulated coins have lost weight to wear, so real content is at or slightly below these figures.
• Ring sizes are conventions laid over a diameter in millimetres. National scales do not align exactly, so a converted size is the nearest equivalent, not an identity.
• These are reference constants and standards, not live prices. Nothing here is an appraisal or a valuation.

Where the numbers come from

These are not prices, and the distinction matters for how much you should trust them. They are defined units, published legal standards, and conversions derived from those. A troy ounce is exactly 31.1034768 grams because it is defined that way, not because anyone weighed one. US silver coin specifications come from the coinage acts that set them. Every derived figure — a coin’s silver content, the ring chart — is produced by running this site’s own functions, so the file cannot disagree with the calculators. Full method on how the numbers work.

Licence

CC BY 4.0. Use it anywhere, including commercially. Attribution is the only condition. If you find something wrong in it, write to us and it gets corrected for everyone.