Is it K or ct or just a 3 digit number? The ‘ct’ is interchangeable with ‘K’ for karat. I’m from Australia so we use ‘ct’ like most Commonwealth countries. The term KARAT refers to the fineness of gold. The word CARAT usually refers to a weight, generally for gemstones but is also used for gold. All a bit confusing, but both are OK to use. The number refers to the fineness of gold in parts per 1000. All these marks are acceptable as it depends on where it was made.

There are many carats used in jewellery. Below are the most common…

  • 8K, 8ct or 333 (parts per 1000) or is 33.3% gold (usually European. Not recognized in USA. The lowest possible standard. Will tarnish sometimes)
  • 9K, 9ct or 375 (parts per 1000) or is 37.5% gold (mainly British Commonwealth countries. Not recognized in USA. Hard wearing.)
  • 10K, 10ct or 416 (parts per 1000) or is 41.6% gold (Minimum USA standard. Hard wearing.)
  • 12K, 12ct or 500 (parts per 1000) or is 50% gold (usually old watch cases. Rarely seen)
  • 14K, 14ct or 585 (parts per 1000) or 58.5% gold (Asian for overseas market. Common in USA. Russian 584.)
  • 15K, 15ct or 625 (parts per 1000) or 62.5 % gold (British Commonwealth countries. Discontinued c1935. A good indicator that the piece is old.)
  • 18K, 18ct or 750 (parts per 1000) or 75% gold. (Most quality pieces are 18ct. Minimum gold standard for sale in Italy.)
  • 22K, 22ct or 916 (parts per 1000) or 91.6% gold (mainly Asia, Middle East. Very soft. Very yellow)
  • 24K, 24ct or 1000 (parts per 1000) or PURE gold (too soft for most jewellery manufacture)
    Rarely you may see something different. The odd ones can be easily be calculated using following…
    1 karat gold is 1 part in 24 gold.
    So for instance 22ct or 22K is 22 parts in 24 of pure gold or 22/24ths or if you multiply 22/24 X 1000 you get 916 (916 parts per 1000) or 91.6% gold.
    If you see a number, for example 625, divide it by 1000 and multiply by 24, it will give you the carat. 625 / 1000 x 24 = 15ct.

Gold comes in many colours depending on the other metals used in the alloy. The carat does NOT change because of the colour. The amount of gold is the same. White, Rose and other are just variations in colour.

ALL gold is stamped or hallmarked with its quality when it is made as required by that countries government, however it’s not unusual to find that marks can be lost through wear or repair. If you are buying an unmarked piece of gold make sure you get an unconditional money back guarantee from the seller as to gold carat or the piece. Then have it checked.
When looking for gold hallmarks make sure that certain marks are NOT on the piece. Things like EP, GP, HGP, (Electroplate, gold plate, hard gold plate) and “rolled”. As the names might suggest, these are NOT solid gold.

A few other numbers to avoid, unless you are into silver, are 800, 925, 950 as these are all silver marks.