A champagne diamond is a diamond which has a light yellow color tint to it. Most champagne diamonds are simply white diamonds rated below K on the color scale, with D being a white diamond that is perfectly colorless. Such tinted diamonds are less valuable than white colorless diamonds, which are much rarer. However, calling a tinted white diamond a champagne diamond makes it more marketable than describing the diamond according to the color scale as 'light yellow' or 'yellow.'
White 'champagne' diamonds are judged on the same qualities as all white diamonds: cut, color, clarity, and carat. The yellow tinge lowers its overall value, but cut, clarity, and carat can still be very high.
A yellow-brown diamond with low gem value can also be treated with heat to lighten and warm the color. Such champagne diamonds cost more than tinted white diamonds, but much less than naturally colored diamonds. As it becomes more common and acceptable to apply heat and other treatments to diamonds, the availability of these diamonds also rises.
Much more rarely, a natural fancy yellow diamond or light pink diamond may also be described as a champagne diamond, although it is more usual to describe these diamonds using the chart for colored diamonds. These types of champagne diamonds command premium prices. For this reason, most diamond retailers will specify that these types of diamonds are natural colored diamonds, which changes the scale for their appraisal, and not simply off-color whites.
Yellow colors in champagne diamonds are caused by interaction with nitrogen during the stone's formation. Nitrogen which is evenly dispersed throughout the diamond creates a canary color.
Champagne diamonds come from kimberlite and lamproite pipes, just the same as regular gem diamonds. Roughly 1 in every 200 kimberlite pipes contain gem-quality diamonds. Major kimberlite deposits can be found in Africa, Russia, Canada, India, Brazil, and Australia. Nearly half of all diamonds come from kimberlite pipes in central and south Africa. However, most champagne diamonds come from the Argyle diamond pipe in Western Australia, the only economically viable lamproite pipe discovered to date.
Other terms are also used to describe yellow-tinted diamonds. Among the most common are sherry diamonds and cognac diamonds.
Many people prefer the warm glow of champagne diamonds to more icy D class diamonds. With the lower price, it is also possible to buy a larger stone, with fewer flaws and a better cut. This may account for some of the popularity of champagne diamonds in engagement rings.