Ok here is a good one for you. I had a very sharp customer come in with exactly one ounce of 14 kt gold. He looked me in the eye and said "You know gold is $1300 dollars an ounce"
I said yes it is but what you have here sir is only 58.5% gold not 100% gold.
Slightly stunned he realized that I was correct and started to laugh.
Almost always Gold Jewelry is a composition of other metals what is known as an alloy. It is comprised of gold, copper, silver, platinum, palladium, and zinc. Some metals are added to increase hardness or to change the hue. Hence white gold, rose gold, etc. The reason this is done are many, one of the main reason is pure gold is extremely soft. It is not suited very well for jewelry it bents and dents very easily.
I am sure you have jewelry that has a mysterious three digit number and no other indication of its gold content or Karat. Well here is a little tip that can help you crack the code.
417 is 41.7% gold content or 10kt.
585 is 58.5% gold content or 14kt.
750 is 75% gold content or 18kt
.999 is 100% gold content or 24kt.
I hope this helps you in the future.