What does 18KGP mean on a jewelry stamp?
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- Issue Time
- Oct 3,2026
What does 18KGP mean on a jewelry stamp?
18KGP = 18 karat gold plated. The three letters answer two questions at once: the gold on the surface is 18-karat (75% pure gold), and it got there by electroplating onto a base metal — in fashion jewelry, most often brass. What the stamp does not say is how much gold is in the piece, because the gold lives only in a micron-scale surface layer.
Read the stamp, then verify the spec
- The karat part (18K) tells you the tone and purity of the gold layer — the warm color buyers associate with fine jewelry.
- The GP part tells you the construction: plated, not solid. A close cousin, 18KGEP, says the same thing with the electroplating process spelled out.
- What the stamp cannot show: plating thickness and adhesion. Those two specs decide how the piece wears, so ask for them in writing — at Hengdian (HD) Jewelry our 18K layer runs 0.1-0.3 micron over polished brass as our own factory standard, with thicker builds available on request.
For wholesale buyers, the practical takeaway is simple: an 18KGP stamp is a starting point for the conversation, not the finish line. Confirm the plating spec and compliance documents before committing to volume — our team on WhatsApp can send both with a quotation.