Question

What do you mean by 18 carat gold?

Answer 1

Gold that is 75.00 – 79.16% pure gold metal.

Explanation:

Gold that contains 99.95% pure gold or more is known as "24 carat". There are various other grades, with lower carat numbers, including 18 carat which contains between 75.00 and 79.16% pure gold, and 14 carat, which is 58.33 to 62.50% pure gold..

The high value of gold means that for many applications it does not make sense to use the pure substance. Pure gold is quite soft, and also for making certain items pure gold would make the cost too high. Adding lower priced metals (copper or silver) to the gold adjusts hardness and reduces the cost of product.

In fact it isn't possible to obtain absolutely pure (100.000%) gold, but you can get close to it.