COLOR Diamond color is graded on a scale of the alphabet, using letters D through Z. The letters A, B, and C aren’t used. This is because when the Gemological Institute of America invented the scale they wanted to disassociate it from jewelry stores that used their own color grade scales. The colors D, E, and F are considered to be completely colorless. D is of course, the best. Some famous diamonds are actually leaning towards the Z end of the scale but aren’t quite “Fancy colored”, like the faint yellow 55-carat Sancy Diamond. The largest known D-color diamond in the world is the Centenary, which weighs 273.85 carats. The second largest is probably the Millennium Star, which weighs 203.04 carats. Some diamonds do not fit onto the scale, such as fancy colored diamonds. Diamonds occur in every color of the rainbow. The rarest colors are red and purple, and combinations of those two colors. Yellow and brown are the most common color of diamond, but colorless is the most popular as far as jewelry is concerned. (Colored diamonds are very gradually appearing in more and more jewelry stores as they become more well-known.) Blues and greens are very rare, especially naturally colored stones. Some lightly colored diamonds (light light pink, light light blue, ect.) are irradiated to make their color more intense. This means that low fields of radiation are beamed into the cut and polished stone, darkening the outer part of the stone all the way around. The process is permanent and professionally accepted in the diamond industry. Probably the largest irradiated diamond is the Deepdene, a 104.88-carat golden yellow cushion shaped stone.
A natural fancy colored diamond will cost you much much more than an irradiated one. Such well known diamonds as the Hope, the Dresden Green, the Tiffany Yellow, the Conde Pink, and Sultan of Morocco, the Transvaal Blue, the Wittelsbach, the Agra, and the Great Chrysanthemum are all very very unique because they were not irradiated. One remarkable stone, the Dresden Green, stands out amoung the naturals. It is the largest green diamond in the world at 40.70 carats. The fact it is an historic diamond, quite large and a natural green color with a slight blue overtone makes it virtually priceless. The Hope is also very unusual for the same reasons, but much more famous. The stone was originally a rather flat, blocky 110-carat rough. It was cut into a triangular pear of 68 carats, and then again into the 45.52-carat cushion cut it is today. The Conde Pink is a pear shaped 9.01-carat pink stone once owned by Louis XIII, also a naturally colored diamond.
In 1988, Sotheby’s Auction House sold a round, 0.90-carat, VS2 clarity, vivid green of natural color for $663,000 to an American collector. The per-carat price was over $736,000. This per-carat price is second to the 0.95-carat Hancock Red Diamond that sold also at Sotheby’s for $880,000 (or $926,315 per-carat) on April 28, 1987. The stone is rumored to have been bought by a man representing the Sultan of Brunei, who is said to have one of the largest colored diamond collections in the world. All in all, a colored diamond is going to cost more than a colorless one, but colorless diamonds will probably always be more popular in the market.
CARAT Carat weight is the most deciding factor as to the value of a diamond. A well cut diamond of SI1 clarity and a weight of 4.00 carats would be worth alot more than one of the same clarity, but weighing 1.60 carats and VS2 clarity.
The largest faceted diamond in the world is the Golden Jubilee, weighing 545.67 carats. It is a Fancy Brownish-Yellow color and “fire rose cushion cut.” It is unusual also because it has a certain type of rare color banding. The second largest faceted diamond in the world is the Star of Africa, also known as the Cullinan I. It weighs 530.20 carats and is a pear shape with 74 facets. The third largest diamond in the world is the Incomparable. It is a golden yellow-orange color, pear shaped, and weighs 407 carats. The fourth largest faceted diamond in the world is the Cullinan II. It was cut from the same stone as the Star of Africa – aka Cullinan I. It weighs 317.40 carats and is a cusion cut.
Up until 2001, the most valuable diamond (price-per-carat) was the 0.95-carat fancy red Hancock Red that had been sold at auction at Christies, NYC, for $880,000 ($926,315 per-carat). The stone was apparently purchased by a buyer representing the Sultan of Brunei, who reputedly has one of the largest collections of fancy colored diamonds in the world.
Some famous fancy colored diamonds
Original document: http://famousdiamonds.tripod.com