hi,
In the U.K., for example, the following caratages are allowed: 9 (375), 14 (585), 18 (750), 22 (916), and 24 (990 and 999). In many countries, a large range of caratages is legally allowed but only a few are in common use. The dominant caratage also varies as shown in the next table:
Typical Caratages of Gold Jewellery
Region
Typical Caratage (fineness)
Oriental East (China, Hong Kong, Taiwan)
24 carat 'Chuk Kam' (99.0% min)
India & subcontinent
22 carat (91.6%)
Arabic countries in Persian Gulf region
21 carat (87.5%)
Europe - Southern */ Mediterranean
18 carat (75.0%)
Europe - Northern, USA, etc**
8-18 carat (33.3 - 75.0%)
- Portugal - 19.2 carat (80.0%)
** For example, Germany - 14 ct with 8 & 18 carat;
UK - 9 ct with 18 and 22 ct;
USA - 14 ct with 10 & 18 carat
Some countries insist that there is no negative tolerance allowed (e.g. UK, where 18 carat is 750 fineness minimum) but in others a negative tolerance, typically 3 parts per thousand, is allowed (e.g. in USA, a fineness of 747 would be accepted as 18 carat). This causes difficulty in the mutual recognition of national marks/hallmarks , a problem raised in the European Union by the Houtwhipper ruling recently. Thus a piece of jewellery assaying at 747 fineness would pass in the USA as 18 carat but fail in the U.K