What Does G18K Mean? 750, 18K and GP Gold Stamps

What does G18K mean?

G18K means 18-karat gold. The G stands for gold, and 18K means 18 parts gold out of 24, or 75% gold. The other 25% is a mix of metals such as silver, copper, zinc or palladium, added to make the gold harder and to set its color.

You will see G18K most often on jewelry made in China and Hong Kong, including many gold-set jade pieces. It is a purity mark, the same idea as a "925" stamp on sterling silver. It does not tell you who made the piece or how much gold it contains by weight.

Because jade jewelry is often bought far from where it was made, buyers in Thailand, Vietnam and elsewhere regularly ask whether G18K is "real gold". If the stamp is honest, yes: it is solid gold, simply not pure gold.

What do 750, Au750, 18K and other gold stamps mean?

Gold purity is written in two systems: karats (parts out of 24) and fineness (parts per 1,000). Different countries and makers use different marks for the same metal.

Karat	Gold content	Fineness stamps	Other marks you may see
24K	99.9% or more	999, 9999	Au999, 足金, 千足金
22K	91.6%	916	Au916
18K	75%	750	G18K, Au750, G750, K18, 18KT
14K	58.5%	585	14KT, K14
9K	37.5%	375	9KT

Some notes on the table:

• Au is the chemical symbol for gold, so Au750 simply means 750 gold. Chinese jewelry commonly uses Au750 or 18K金.
• K18 with the K first is common on Japanese jewelry.
• Thai gold sold by weight in gold shops is 96.5% gold, between 22K and 24K. In Thailand, lower-karat gold such as 18K is usually called ทองเค (K gold) and is sold mainly as jewelry, not traded like 96.5% gold.
• In Vietnam, 18K is called vàng 18K or vàng 7 tuổi rưỡi (7.5 out of 10 parts gold), and 750 Italian-made gold is often sold as vàng Ý.

What do GP, GEP, HGE, RGP and GF mean?

These letters mean the piece is not solid gold. The gold is only a surface layer over another metal such as brass, copper or silver.

Stamp	Stands for	What it is
GP	Gold plated	A very thin gold layer, usually by electroplating
GEP	Gold electroplated	Same as GP
HGE	Heavy gold electroplate	A thicker plated layer, still not solid gold
RGP	Rolled gold plate	A thin sheet of gold bonded to base metal
GF	Gold filled	A thicker bonded gold layer, more durable than plating
Vermeil	Gold over silver	Gold plating on sterling silver

So "18K GP" is plated, not 18K gold. The "18K" only describes the color or the gold used in the plating. Plated pieces can look identical when new, but the color wears off at edges and contact points, and the metal underneath has little resale value.

Watch for stamps that mix the two, such as "18K GP" in small letters next to a large "18K". Read the whole mark with a loupe.

Is the stamp proof that it is real gold?

No. A stamp is the maker's or seller's claim. Fake and plated pieces can be stamped G18K or 750, and some genuine pieces are not stamped at all, especially small parts like bails and earring hooks.

How to check:

Method	What it tells you	Notes
Read the stamp with a loupe	The claimed purity, and any GP or GF letters	A first check only
XRF test at a gold shop	Gold content of the surface, in seconds	Non-destructive; many gold shops in Thailand and Vietnam have one
Touchstone and acid	Whether the metal reacts like gold of a given karat	Leaves a small streak; best done by a professional
Magnet	Gold is not magnetic; some cheap base metals are	Only rules out some fakes; plated brass is not magnetic either
Weighing	Compare with a known gold piece of the same size	Rough; jade and stones add weight

For a piece with a lot of gold, an XRF reading at a reputable shop is the practical answer. Note that XRF reads the surface, so a thick plating can sometimes fool it; for high-value pieces, ask the shop about deeper testing.

Why is jade usually set in 18K gold?

• Strength. Pure 24K gold is soft and bends easily, so prongs and bezels can loosen and let the stone fall out. 18K holds a stone securely.
• No tarnish. 18K does not darken the way silver does, which matters for pieces worn every day.
• Color choice. 18K comes in yellow, white and rose. White gold flatters icy and pale green jade; yellow gold warms up deeper greens and red or yellow jadeite.
• Value. It is three quarters gold, more than 14K, so it suits valuable stones.

White gold and rhodium. 18K white gold is naturally slightly grey-yellow, so it is usually coated with rhodium for a bright white finish. With wear the coating thins and the setting looks warmer. A jeweler can re-plate it; this is normal and not a sign of fake gold.

For more on choosing a metal, see jade in sterling silver vs 18K gold and gold-set jadeite.

How much of the price is the gold?

In most jade pendants, rings and earrings the gold weighs only a few grams, so the jade decides most of the price. Two pendants with similar settings can differ many times in price because of the stone's texture and color. If the gold matters to you, ask the seller for the gold weight in grams; "18K" alone does not tell you how much gold there is.

Selling gold-set jade back is a different matter. Gold buyers price the metal, not the jade, and jade buyers price the stone. In Thailand, whether a gold shop buys 18K jewelry and at what rate depends on the shop, so ask first. See jadeite resale value.

What gold do JadeiteHub settings use?

All gold settings, bails and earring parts on JadeiteHub pieces are solid 18K gold, in yellow or white. A few pendants are set in 925 sterling silver, and the listing says so. Examples, prices as of 2026-10-31:

Piece	Setting	Price
JH-000004 icy green wu shi pai pendant	18K white gold	US$2,919
JH-000025 icy white seated Buddha pendant	18K gold	US$8,889
JH-000232 full green cabochon ring	18K gold	US$7,189

Every piece is certified natural Type A jadeite and ships with its own certificate from an accredited Chinese national gem lab (国检); the certificate covers the jadeite. If a piece does not match its description, you get a full refund. Browse all JadeiteHub pendants and rings and earrings.