900
900 (coin silver / PT900) · 90% pure
Silver · Platinum
900 means 90% pure. On platinum it's PT900 — 90% platinum, a common grade especially in Japan, a little more alloyed than PT950. On silver, 900 is “coin silver”: historically the standard struck from melted coinage in the United States and elsewhere, 90% pure and harder than sterling.
Hallmark Translator
Translate a purity you know into how any country marks it — gold, silver, platinum, palladium — or compare two countries side by side.
Why 90%?
Before sterling became dominant, much American and continental silver was made at 900 — the fineness of silver coinage — so old flatware and pieces stamped “COIN” or “900” are 90% silver, harder and slightly greyer than sterling.
On platinum, Japan's strong platinum market uses both 900 and 950; PT900 is a touch harder and more alloyed than the higher PT950.
900, metal by metal
The same number means the same purity on every metal — but what it's called, and the mark struck beside it, changes with both the metal and the country.
On silver
Coin silver — 90% pure, historically made from melted coin; harder than sterling. Seen on older American and continental pieces.
Independent assay
On platinum
PT900 — 90% platinum, a common fine grade, especially in Japan; slightly more alloyed than PT950.
Independent assay
Mandatory maker's mark
What people actually ask
What is coin silver / 900 silver?
Silver that's 90% pure, historically made from melted coinage — harder and slightly greyer than sterling. Often stamped “COIN” or “900”.
What is PT900?
90% pure platinum — a common platinum grade, especially in Japan, a little more alloyed than PT950.
PT900 vs PT950 — which is better?
PT950 is purer (95%) and the higher standard; PT900 (90%) is slightly harder. Both are solid platinum.
Is 900 silver real silver?
Yes — 90% pure silver, the rest copper. Solid silver, not plated.
A reference guide, not an authentication service. The same number can appear on different metals, and the mark beside it varies by country, date and maker — consult the relevant assay office or standards body for definitive identification.