Since ancient times, gold has been used to create the finest objects of art, religious articles and fine jewelry. Because gold can be mixed with other metals to create different colors and karats, it is one of the most popular metals for jewelry today in the United States and Europe. Gold, as a precious metal, has been valued and held in high esteem since ancient times and is still one of the most highly prized metals that has, throughout the ages, been used to symbolize wealth and power.
Jewelry made of higher-karat gold is more yellow in color and slightly softer than gold jewelry made of lower-karat gold, which may include copper, silver, zinc, or other metals. The consumer needs to be concerned with the alloys if you are allergic to certain metals or have a high acid content in your body. Acid can turn the jewelry that you wear on your body to black and appear to be of poor quality when it actually is not. Pure gold (which is always yellow) is too soft for jewelry use. The metals that are mixed with pure gold for strength can also modify the color of gold resulting in different shades of yellow, white, and pink gold. White gold was originally developed to imitate platinum, and is usually an alloy containing 25% nickel and zinc. If stamped 18 karat, it would be 75% pure gold. Here is the table that shows the purity of gold by karat:
|Karatage||% of Fine Gold||Karatage||% of Fine Gold||Karatage||% of Fine Gold|
24 karat gold is pure gold. The term "karat" refers to the percentage of gold, versus the percentage of other metals, in an alloy (an alloy is a substance made of two or more metals).
Since gold is too soft to be usable in its purest form, it is usually combined with other metals. The most common marks for gold jewelry are 18K or 750 (signifying 75% gold), 14K or 585 (58% gold), and 10K (42% gold).
To regulate the use of gold, the United States passed the National Gold and Silver Stamping Act, which states that if an item is marked with its quality, that mark should be accurate and within the tolerances provided by the Act. Ten karat gold is the lowest level allowed under U.S. law.
There is no such thing as naturally occurring rose, white, or green gold. Gold itself is only one color: yellow. White gold and yellow gold are the most common types of gold colors used in jewelry making. But did you know that, various other colors of gold are also available and some of these colors may surprise you. Gold is available in several different colors. The most popular is yellow gold, followed by white gold and rose gold, though other gold colors are sometimes also available such as bronze, red and lime gold. All of these other "colors" of gold are produced by mixing pure 24K yellow gold with various other metals. The percentage of the other metals (copper, silver, zinc, nickel) produces the different shades of gold. Any karat other than 24K gold (pure gold) is called an "alloy". For instance, 14K gold is an alloy consisting of fourteen parts pure gold and ten parts other metals.
White gold was originally developed to imitate platinum, and is usually an alloy containing 25% nickel and zinc. If stamped 18 karat, it would be 75% pure gold. White gold is an alloy of gold and at least one white metal, usually nickel or palladium. Like yellow gold, the purity of white gold is given in carats (karats). Eighteen-carat white gold consists of 75% gold mixed with 25% white metals. New white gold rings are usually coated with a hard protective finish of rhodium, a silver-white metal like platinum. To keep a white gold ring looking its best, Gillett's recommends an annual replating of rhodium, since the coating wears off over time. White gold has become very fashionable in recent years as many consumers have opted for the cool, contemporary white look over the classic yellow look. White gold has the same properties as yellow gold, but is mixed with different alloys to give it its white color. Generally, white gold is created by using a nickel or palladium alloy, zinc and copper. Sometimes, white gold is plated with an even whiter metal, such as rhodium (a rare member of the platinum family) to enhance its appearance. A white gold setting can enhance the look of white diamonds and put a modern twist on a traditional standard.
Rose gold is a gold and copper alloy widely used for specialized jewelry due to its reddish color. It is also known as pink gold and red gold. Because it was popular in Russia at the beginning of the nineteenth century it is also known as Russian gold, although this term has become somewhat rare. Since it is an alloy, there is no such thing as "pure rose gold"; pure gold is yellow and pure copper is reddish. Although the names are often used interchangeably, the difference between red, rose, and pink gold is the copper content. Rose gold, also known as pink gold or red gold, is a mixture of pure yellow gold with a high percentage of copper. It has a very subtle and delicate color that may intensify somewhat with age due to a slight, but attractive, tarnishing of the copper.
Because of the softness of pure (24k) gold, it is usually alloyed with base metals for use in jewelry, altering its hardness and ductility, melting point, color and other properties. Alloys with lower caratage, typically 22k, 18k, 14k or 10k, contain higher percentages of copper, or other base metals or silver or palladium in the alloy. Copper is the most commonly used base metal, yielding a redder color. Eighteen carat gold containing 25% copper is found in antique and Russian jewelry and has a distinct, though not dominant, copper cast, creating rose gold. Fourteen carat gold-copper alloy is nearly identical in color to certain bronze alloys, and both may be used to produce police and other badges. Blue gold can be made by alloying with iron and purple gold can be made by alloying with aluminum, although rarely done except in specialized jewelry. Blue gold is more brittle and therefore more difficult to work with when making jewelry. Fourteen and eighteen carat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. White gold alloys can be made with palladium or nickel. White 18 carat gold containing 17.3% nickel, 5.5% zinc and 2.2% copper is silver in appearance. Nickel is toxic, however, and its release from nickel white gold is controlled by legislation in Europe. Alternative white gold alloys are available based on palladium, silver and other white metals (World Gold Council), but the palladium alloys are more expensive than those using nickel. High-carat white gold alloys are far more resistant to corrosion than are either pure silver or sterling silver. The Japanese craft of Mokume-gane exploits the color contrasts between laminated colored gold alloys to produce decorative wood-grain effects.
Because gold is a very good conductor of electricity and heat, it is widely used for industrial purposes and manufacturing applications. Gold was once used extensively as dentures and dental fillings because of it's soft demeanor and it's easiness to shape. Although it is still used in some dental applications, it is not used for dentistry purposes as extensively today. Other usages gold include biological and medical research, photographic imaging, and because it is has a high resistance to corrosion, it is used in sensitive instruments and other mechanical devices.
Gold has been known and highly-valued since prehistoric times. It may have been the first metal used by humans and was valued for ornamentation and rituals. Egyptian hieroglyphs from as early as 2600 BC describe gold, which king Tushratta of the Mitanni claimed was "more plentiful than dirt" in Egypt. Egypt and especially Nubia had the resources to make them major gold-producing areas for much of history. The earliest known map is known as the Turin papyrus and shows the plan of a gold mine in Nubia together with indications of the local geology. In ancient Egypt, around the time of Seti I (1320 B.C.), we find the creation of the first gold treasure map now known to us. The primitive working methods are described by Strabo and included fire-setting. Large mines also occurred across the Red Sea in what is now Saudi Arabia.
Gold was first discovered as shining, yellow nuggets. "Gold is where you find it," so the saying goes, and gold was first discovered in its natural state, in streams all over the world. No doubt it was the first metal known to early hominids.
Early civilizations equated gold with gods and rulers, and gold was sought in their name and dedicated to their glorification. Humans almost intuitively place a high value on gold, equating it with power, beauty, and the cultural elite. And since gold is widely distributed all over the globe, we find this same thinking about gold throughout ancient and modern civilizations everywhere.