What you should know before you sell your gold.

24k gold is very soft. As such gold is usually mixed with base metals when making jewelry (see the post below explaining the karat system). The metals are mixed to create what is called an alloy.

Gold may be mixed with copper, silver, palladium, zinc, nickel or other metals. While pure gold is a metallic yellow, many other “colors of gold” can result when alloyed with a base metal. For example, an abundance of copper alloyed to gold will create a red, copper cast. This is usually called rose gold. White gold is gold that has been alloyed with nickel or palladium, or sometimes nickel, zinc and copper. Even blue and purple gold can be made by alloying gold with iron or aluminum.

While some gold alloys may hold a higher value than other alloys. The real value in your gold jewelry is in the amount of gold it contains. Gold is alloyed with silver, copper, nickel or zinc for most applications.
More weight + more karat, usually = more value:

• 24 karat gold - 100% Au - pure gold, very soft and very easily bent, too soft for jewelry  
• 22 karat gold - 91.7% Au - still too soft for most jewelry 
• 18 karat gold - 75.0% Au - use for fine jewelry, the best for beauty and durability 
• 14 karat gold - 58.3% Au - is OK for jewelry, but the gold is of a duller color 
• 12 karat gold - 50.0% Au - is not OK for most western jewelry 
• 10 karat gold - 41.7% Au - is the legal limit for 'real' gold in USA
• Gold Star Jewelry Pays More for Your Gold