Quality Guide
| sizes chart | GIA 4Cs | Gold Purity |
Size Chart
| diameter, mm | circumference, mm | EU | RU | JP | US | UK |
| 13.0 | 40.8 | 41 | 41 | 1 | 1.75 | C½ |
| 13.5 | 42.4 | 42 | 42 | 2 | 2.25 | D½ |
| 14.0 | 44.0 | 44 | 44 | 4 | 3.0 | F |
| 14.5 | 45.6 | 46 | 46 | 6 | 3.5 | G |
| 15.0 | 47.1 | 47 | 47 | 7 | 4.25 | H½ |
| 15.5 | 48.7 | 49 | 49 | 9 | 4.75 | I½ |
| 16.0 | 50.3 | 50 | 50 | 10 | 5.5 | J½ |
| 16.5 | 51.8 | 52 | 52 | 12 | 6.0 | L |
| 17.0 | 53.4 | 53 | 53 | 13 | 6.5 | M |
| 17.5 | 55.0 | 55 | 55 | 15 | 7.25 | N½ |
| 18.0 | 56.5 | 57 | 57 | 17 | 7.75 | O½ |
| 18.5 | 58.1 | 58 | 58 | 18 | 8.5 | Q |
| 19.0 | 59.7 | 60 | 60 | 20 | 9.0 | R |
| 19.5 | 61.3 | 61 | 61 | 21 | 9.75 | S½ |
| 20.0 | 62.8 | 63 | 63 | 23 | 10.25 | T½ |
| 20.5 | 64.4 | 64 | 64 | 24 | 11.0 | V |
| 21 | 66.0 | 66 | 66 | 26 | 11.5 | W |
| 21.5 | 67.5 | 68 | 68 | 28 | 12.25 | X½ |
| 22.00 | 69.1 | 69 | 69 | 29 | 12.75 | Y½ |
| 22.5 | 70.7 | 71 | 71 | 31 | 13.5 | Z½ |
| 23.0 | 72.3 | 72 | 72 | 32 | 14.0 | Z+2 |
| 23.5 | 73.8 | 74 | 74 | 34 | 14.5 | Z+3 |
| 24.0 | 75.4 | 75 | 75 | 35 | 15.25 | Z+4½ |
| 24.5 | 77.0 | 77 | 77 | 37 | 15.75 | Z+5½ |
| 25.0 | 78.5 | 79 | 79 | 39 | 16.5 | Z+6 |
GIA 4Cs
| GIA Color Scale | |
| colorless | D |
| E | |
| F | |
| near colorless | G |
| H | |
| I | |
| J | |
| faint | K |
| L | |
| M | |
| Very light | N |
| O | |
| P | |
| Q | |
| R | |
| Light | S |
| T | |
| U | |
| V | |
| W | |
| X | |
| Y | |
| Z |
| GIA Clarity Scale | |
| flawless | |
| internally flawless | |
| Very very slightly included | VVS1 |
| VVS2 | |
| Very slightly included | VS1 |
| VS2 | |
| slightly included | SI1 |
| SI2 | |
| included | I1 |
| I2 | |
| I3 |
| gia cut scale |
| excellent |
| very good |
| good |
| fair |
| poor |
| Carat weight |
| Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip. (Don’t confuse carat with karat, as in “18K gold,” which refers to gold purity.) Just as a dollar is divided into 100 pennies, a carat is divided into 100 points. For example, a 50-point diamond weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on the other members of the Four C’s: clarity, color and cut. The majority of diamonds used in fine jewelry weigh one carat or less. |
Source: Gemological Institute of America (GIA)
Gold Purity
‘Caratage’ is the measurement of purity of gold alloyed with other metals. 24 carat is pure gold with no other metals. Lower caratages contain less gold; 18 carat gold contains 75 per cent gold and 25 per cent other metals, often copper or silver.
Fineness is another way of expressing the precious metal content of gold jewellery, and represents the purity in parts per thousand. When stamped on jewellery, usually this is stated without the decimal point.
The following are the common standards of fineness that are used – .585 (.583) = 14 carat (14K) and .750 = 18 carat (18K).
Source: Gold World Council