bling aijewelry stamps · silver & platinum
solid metal900 stamp on jewelry: what it means.
900 means the metal is 90% pure. on silver it's coin silver, common on antique pieces; with Pt or Plat beside it, it's 900 platinum.
- on silver
- coin silver
- 90% silver
- on platinum
- 900 platinum
- 90% platinum
- also stamped as
- 900 · .900 · coin · Pt900 · 900 Plat
what it's worth today
live spot price · updated Sep 24, 2026, 12:47 AM UTC
melt value of the metal only, from the live spot price. buyers pay less than melt; stones, craftsmanship and maker add value.
the mark
what 900 means.
on silver, 900 is coin silver: the same 90% standard once used for american and european silver coins. silversmiths in the 1800s often made spoons and jewelry from it, sometimes by melting coins, before sterling became the norm.
on platinum, 900 means 90% platinum. it's common in japanese jewelry and on some older pieces, and it's usually marked Pt900 so it isn't confused with silver.
if there's no Pt or Plat on the piece, and it's not unusually heavy, a 900 stamp almost always means coin silver.
before you trust it
how to check a 900 stamp.
- look for letters beside the number. Pt, Plat or Platinum means platinum; COIN or no letters on an older piece usually means coin silver.
- compare the weight. platinum is roughly twice as dense as silver, so a platinum piece feels far heavier than a silver one of the same size.
- hold a strong magnet to it. silver isn't magnetic, so a piece that clings to the magnet is plated steel or another base metal.
- for certainty, ask a jeweler or gold buyer for an XRF scan. it reads the metal's composition in seconds without scratching the piece, unlike an acid test.
questions
the 900 stamp, answered.
other stamps
every mark is searchable in the hallmark decoder. selling vintage or estate pieces? see photography for vintage and estate sellers.
selling what you found?
photograph it like it's worth something.
bling ai turns a phone photo of a piece into a listing shot that looks like a campaign, so good jewelry sells for what it is.
