Karat
Karat (K) is the measurement of the purity of gold, with the purest form measuring 24K. Although pure gold is the most valuable and expensive form of gold, it is not ideal for jewelry as it is too soft and vulnerable to damage from everyday wear. To make durable and wearable gold jewelry, metal alloys such as copper, nickel, silver, and zinc are blended with pure gold to create 22K, 18K, 14K, and even 10K gold jewelry.