Gold is rated according to its level of purity. The alloy in the gold increases as the purity of gold decreases. The most common alloys used when making gold jewelry are copper and silver. Nickel alloy is often used to make white gold. The bottom line: The higher karat weight a gold piece of jewelry has, the more valuable it will be. Let's look at the most common karat weights for gold.
Measure the karat weight of gold by its purity, with 24 -karat gold being pure gold.
Check 22-karat gold, which has a purity of 22/24 or 91.7 percent.
Examine 18-karat gold, which has a purity of 18/24 or 75 percent.
Observe 14-karat gold, which has a purity of 14/24 or 50 percent.
Weigh 10-karat gold, which has a purity of 10/24 or 41.6 percent.