the gold is made by weight, and then alloyed to be more durable. One oz of gold alloyed into 14k or 18k will sell for the same amount as one oz of 24K. if you want to buy it and purify it yourself, I can tell you how to do that too.....
What that site claims is that the gold is sold by actual weight of the gold content.... Not the weight of the jewelry....
I put out this disclaimer, I have not bought from them, nor am I affiliated with them....