Gold is one of the most precious metals in the world. It is expensive and difficult to extract but the many desirable qualities found in gold, along with its scarcity, have made it the most popular metal for use in jewelry today.
In America and Europe gold jewelry is made from gold alloy and the purity of this alloy is stated in Karats. By definition, the karat system is used to reveal the amount of pure gold found in an item.
- 24 karat (24K) gold is pure gold.
- 18 karat (18K) gold contains 18 parts gold and 6 parts another metal or metals, making it 75% gold.
- 14 karat (14K) gold contains 14 parts gold and 10 parts another metal or metals, making it 58.3% gold.
- 10 karat (10K) gold contains 10 parts gold and 14 parts another metal or metals, making it 41.7% gold. 10k gold is the minimum karat designation that can still be called gold in the US.
Karat Value Definitions:
- Karat System: A system of measurement based on 24 karats being “fine” or “pure” gold. 1 karat equals 1/24th fine gold by weight. This is the system used in the United States.
- Plumb Gold: Karat weights are usually determined with a small, fractional variance allowed. Karat gold which has no variance and is exactly the precise fractional karat weight is called “plumb” gold.
- European System: A system of measurement based on a fraction of 1,000; or the number of grams of gold in 1 kilogram of alloy.
Gold in its pure state:
- Has a melting point of 1945 degrees Fahrenheit (1063 degrees Celsius). When alloyed (chemically combined) with other base metals the melting temperature of the resulting alloy is changed. 18K yellow gold has a melting point of 1675 degrees Fahrenheit and 14K yellow gold has a melting point of about 1550 degrees Fahrenheit.
- Has a specific gravity of 19.33. It is relatively heavy compared to most metals, such as silver (SG 10.7) or iron (SG 7.8). A notable exception is platinum (SG 21.4).
- Is more malleable than any other metal and can be hammered into foil so thin that it is almost transparent.
- Has a unique ductility property allowing it to be drawn into wire so fine it can barely be seen.
- Is deep yellow in color. Its great reflectivity properties help keep its brightness and color from fading with time.
- Will not rust, tarnish or corrode. Gold jewelry recovered from ancient Egyptian tombs is in the same state as when placed there over 4000 years ago.
- Is softer than most other metals. On the Mohs scale of hardness (which is a measure of a gemstone or mineral’s resistance to scratching), gold has a hardness value of 2 to 2.5. Diamond has a value of 10. Pure gold may easily be scratched. Fortunately, gold becomes harder when alloyed with other base metals.
- Is relatively scarce and therefore expensive. It is estimated that only 125,000 tons of gold have been mined the world over since the beginning of time.
- Is able to bond with other base metals. This property gives rise to the many different colors available in modern gold alloys.
Tags: classic jewelry, gold, gold jewelry
