Diamonds are graded on color from D – Z, with D perfectly clear and white in overtone and having no color whatsoever. The further down you get on the scale, the more yellow, brownish, or grayish a diamond can look. Because diamonds are a product of nature, each one is formed differently and sometimes another element has become trapped in the carbon as the diamond is forming. This isn’t necessarily a bad thing.
This is how we get blue diamonds, pink diamonds and the ultra rare red diamonds. But most commonly the color changes on a diamond will go from white to yellow. Typically going up one grade in color can result in about a 15% increase in cost on the stone. It’s not a hard and fast rule, but a general rule of thumb.