The most popular, and most versatile, metal used in jewelry is gold. It comes in three different forms, yellow gold, white gold, and rose gold. Yellow gold is the most common form of gold, followed by white gold, and finally rose gold. The purity of the gold is measured in karats, going from 10k to 24k. Despite 24k being one of the purest forms of gold, it is too soft and malleable for everyday use, hence why 14k is typically used in jewelry, as the other metals in it give it the strength it needs.
Sterling silver, also known as 925 silver, is the next most common metal used in jewelry making. Stamped as 925 because it contains 92.5% pure silver, it is just hard enough that it can be used in everyday instances, but is still able to be shaped and formed by jewelers. It is the most cost effective option due to the large supply, but over time it is prone to oxidation, turning black over long periods of wear.
Platinum typically stamped in 950, which is 95% pure platinum. It is known for it's hypoallergenic properties, since it is so pure. Platinum is almost twice as dense as gold, giving the jewelry a much heavier and premium feel. Since it is so dense, it is extremely durable and lasts for a long time. Although it is very dense, it is still very malleable and can easily be manipulated into many shapes. Unlike gold, platinum will fade to a dull gunmetal color due to wear.