Coin and jewelry collectors alike love gold. Though it's used in a variety of products, 75 percent of all gold produced is used for jewelry. Gold is generally yellow, but when it's finely divided it can be black, ruby, or purple. Depending on how it's alloyed, it can have a variety of colors, including white, red and blue. Glass can be colored purple or red with colloidal gold, and metallic gold is often used to line windows, reflecting sunlight.

Gold (Au) is number 79 on the periodic table of elements. Its melting point is 1947.2 degrees Fahrenheit, and it has a boiling point of 5172.8 degrees Fahrenheit. Gold is the most malleable of all metals, which is what makes it perfect for jewelry making. In fact, one ounce of gold can be pounded into a 5 meter long sheet, known as gold leaf, which is commonly used in crafts and other decorative items.

Its softness leads many manufacturers to alloy gold with other metals, such as platinum and silver - the higher the gold content in these alloys, the more valuable the piece of jewelry is. A karat quantifies the amount of gold in an alloy, which can be anywhere from 1 to 24 karats, or pure gold. If you have 14 karat gold ring, it's 14 parts gold, 10 parts alloy material.

As an excellent conductor of heat and electricity, gold is commonly used to make electrical connectors and printed circuit board.

Health problems related to gold exposure are rare, and it's even safe to be ingested. Inhalation or long-term skin exposure could cause irritation, though this is rare. Gold has been even believed to be a remedy for some health conditions, including rheumatoid arthritis.