Gold purity is measured in karats (not to be confused with carats, a measure of gem weight). Karats are divided into 24 parts, so 24 parts of gold - known as 24K gold - is pure. However, 24K gold is soft and easily damaged, so it's mixed - or alloyed - with other metals to make it more durable. For example, 14K gold is 14 parts gold, 10 parts other metal. Jewelry must be at least 10K to be sold as gold in the United States.

Buff your gold engagement ring with a soft cloth to keep it shiny and smooth.

Because of its hardness, the details of intricately engraved or embellished rings often look sharper and more precise when done in platinum. Platinum is durable and naturally white, allowing diamonds and other gemstones to appear even more brilliant.

Platinum is known for its ability to withstand daily wear without thinning. Platinum in jewelry is 90% to 95% pure, which brings out the beauty of diamonds set in platinum engagement rings. It's also hypoallergenic, making it a good choice for those with skin sensitivities. 

Over time, platinum will wear and scratch with use. Your jeweler can polish your platinum wedding band or platinum engagement ring to remove any scratches. Platinum's patina is celebrated by jewelry lovers and designers because it underscores the metal's authenticity. It's also a sign that the ring has strengthened from wear - platinum actually grows stronger every time it's scratched.