The diamonds that come under X-Y-Z color grading scale of GIA displays a tint of yellow, which owes to the inclusion of nitrogen in the diamonds during its formation in the Earth.     The nitrogen atoms are akin to carbon atoms, so much so that it takes the place of carbon in the diamond formation process. Yet again, one need not confuse the X-Y-Z diamonds with fancy yellow color diamonds, which extends beyond X-Y-Z color scale into a Fancy Light color range. Such colored diamonds are sought after since they are rarely found in mining facilities and provide a yellow tone that is striking. If you are looking for an engagement ring with a yellow diamond, it is likely you are on a tight budget. If so, choose yellow diamond engagement ring with X-Y-Z color grade to own it without having to break the bank. In fact, you can own a higher clarity grade and carat weight at a much lower price point. Still, be mindful of the fact that X-Y-Z diamonds with light yellow hue will be pricier than diamonds in the color range from K to P since they will not be as attractive as the former.