The main differences between 24k, 22k, and 18k gold are their purity and composition.

24k gold is the purest form of gold available, containing 99.9% pure gold by weight. It is the softest and most malleable form of gold, which makes it unsuitable for many types of jewelry. Because of its high purity, 24k gold is also more prone to scratching and bending out of shape than lower-karat gold alloys.

22k gold contains 91.67% pure gold and 8.33% other metals, such as copper, silver, or zinc. It is harder and more durable than 24k gold, making it a popular choice for jewelry that is meant to be worn on a daily basis. 22k gold also has a slightly duller, more muted yellow color than 24k gold due to the presence of other metals in the alloy.

18k gold contains 75% pure gold and 25% other metals, such as copper, silver, or zinc. It is less expensive than higher-purity gold alloys, but still has a high gold content that gives it a warm, rich color that is highly prized. 18k gold is more durable than 24k gold, but not as hard as 22k gold, making it a good choice for fine jewelry that is intended for regular wear.

In terms of pricing, 24k gold is typically the most expensive due to its high purity, while 18k gold is typically less expensive than 22k gold. However, the price of gold can fluctuate based on market conditions and other factors.