Sorry to break it to you, but no unfortunately it is not 100%. If you are wearing any jewellery, have a look for the metal hallmark. Your jewellery will have a hallmark to indicate the purity out of a 1000. For example: if your gold jewellery is hallmarked 750, it is 75% pure gold (also known as 18 karat).
9K gold contains 37% pure gold and 63% Alloy.
14K contains 58% pure gold and 42% Alloy.
18K gold contains 75% pure gold and 25% Alloy.
So why not just make it 100%?
Because Gold is too soft for making jewelry especially for everyday use!
SEE MARKS ON YOUR JEWELRY