Gold Karat Hallmarks

On this page:
  1. What is a Karat?
  2. What Karat hallmarks look like?
  3. Gold-Plated and Gold-Filled hallmarks

What is a Karat?

Karat is unit of gold purity, while Carat is used for measuring diamond weight. The spelling is being mixed up sometimes, but the two are not to be confused. While carat for diamonds is a measure of weight, gold karats are in fact percentage of gold in the alloy.

[[ More content to be added about colored gold alloys ]]

What Karat hallmarks look like?

The hallmarks of gold typically consist of a number and two letters.

E.g. 14Kt, 14Kt, 18KP, etc.

[[ I will follow up with some pictures of the stamps later on... ]]

The letters mean: K, k, KT, Kt, kt, CT, ct - are all abbreviations used for karat or carat

KG - Karat of Gold (essentially, the same as the above)

KP - Karat Plumb (manufacturer guarantee of the purity) -- rarely found on common jewelry, and it's confusing because of its similarity to K.P. (for gold-plated jewelry, see below on this page).

The number represents percentage of gold in the alloy. Pure gold is too soft, and jewelry made of pure gold wouldn't last long, that's why alloys of gold are used to make jewelry.

100% pure gold is a non-existing ideal; due to chemical impurities, there's always a little fraction of non-gold component in the metal. That's why 99.9% is the best gold purity being stamped.

Karat is equivalent to 1/24 of the alloy, i.e. approximately 4.27%.

14K therefore is 14/24, i.e. approximately 58.3%. (The actual standards are 58.4% or 58.5%.)

The following table is a compilation of different information sources I've found all over the Internet. It shows all the markings commonly found on gold jewelry.

Karat hallmark Parts of 1000 hallmark Percentage of gold in the alloy Details
8K 333 33.3% Usually European. Not recognized in USA. The lowest possible standard. Will tarnish sometimes
9K 375 37.5% Mainly British Commonwealth countries. Not recognized in USA. Hard wearing.
10K 416, 417 41.6% – 41.67% Minimum USA standard. Hard wearing.
12K 500 50% Usually old watch cases. Rarely seen
14K 585, 584, 583   58.5% – 58.33% Italian and Asian for overseas market. Common in USA. Russian 584 (or 583?)
15K 625 62.5% British Commonwealth countries. Discontinued c1935. A good indicator that the piece is old.
18K 750 75% Most quality pieces are 18ct. Minimum gold standard for sale in Italy.
21K 875 87.5%  
22K 916 91.6% Mainly Asia, Middle East. Very soft. Very yellow
23K 958 95.8% (95.83%)  
24K 1000 99.9% Purest gold theoretically possible - too soft for most jewelry manufacture

Those three-digit hallmarks for gold (nowadays found mostly on Russian jewelry from Soviet period) are easily confused with silver hallmarks, especially 750 mark, which is exactly the same. Inspect your piece carefully, make sure to read all the other hallmarks (Soviet jewelry pieces should have other markings).

[ More on Russian and Soviet gold hallmarks ]


Gold-Plated and Gold-Filled hallmarks

Jewelry made of some base metal and covered by gold would have much less value, but the hallmarks might be confusing for a non-pro. Here are some hallmarks for no-gold-inside jewelry:

K.P. - Karat Plate - (according to some sources on the web, it's not a real stamp, rather used in advertizements by less reputable dealers

GF - Gold Filled

GS - Gold Shell

HGE - Heavy Gold Electroplate

All those are different methods / technologies of covering jewelry product with a layer of gold, or they might represent different amount of gold used in plating... anyways, the amount of gold here is much less than in jewelry made fully of gold. Quick note on gold plating: a distinctively yellow item might have a stamp of 925 or something similar. In this case it's sterling silver covered by gold (see silver hallmarks).
 

What Karat hallmarks look like?