A karat (K) is a unit of purity for gold, where 24K is its purest form. Since 24K gold is too soft to be suitable for use in products like precious jewelry, other metal alloys must be mixed with this element in order to form a stronger, more durable material.
Typically, the purest form of gold used in jewelry is 18K, where 75% of the material is gold and 25% is composed of another metal or metal alloy. Most jewelry in the United States ranges from 10-18K. Higher gold purity typically is used with larger, more precious gemstones and diamonds, but 20K is around the maximum purity strong enough to hold stones.
Facts about Karat