Yellow diamonds receive their color from exposure to nitrogen over the millions of years that a diamond takes to form. Nearly all “white” diamonds contain some slight shade of yellow or brown, and the standard GIA color grading scale allows for that, deeming D, E, or F-grade stones “colorless.”
According to the GIA, K-M grade diamonds are “faint yellow” while N-R graded diamonds are considered “very light yellow.” The remaining letters denote color grades ranging from “light yellow” to “strong yellow.” True yellows account for less than 0.1% of all naturally occurring diamonds.
Yellow diamonds can be found all over the world. While diamonds with intense yellow shades are particularly prevalent in southern and central Africa, the Ellendale Mine in Western Australia is the world’s single largest producer of rare fancy yellow diamonds. The Ellendale Mine is contracted to provide a direct supply of yellow diamonds to renowned jewelers Tiffany & Co, which in April 2010 launched its Yellow Diamond jewelry collection.
The largest yellow diamond known today is the Incomparable – a 407.48-carat stone with a color description of Fancy Brownish Yellow. The Incomparable, mined in the Democratic Republic of Congo, is the third-largest faceted diamond in the world.
The next-biggest yellow diamonds are the Oppenheimer, a 253.70-carat Yellow diamond; the De Beers, a 234.65-carat Light Yellow diamond; and the 205.07-carat Red Cross Diamond – all of which were mined in South Africa.
The fifth-largest yellow diamond in existence is the Florentine Diamond, a 137.27-carat Pale Yellow diamond discovered in India in the 15th or 16th century. The Florentine was owned by the Medici family and later by the Hapsburgs, eventually becoming part of Austria’s Crown Jewels.