Darya-I-Nur diamond is believed to be the largest pink diamond in the world. The stone is estimated to weigh somewhere between 175 and 195 carats, and it is a light pink color. Its exact weight isn't known because its been mounted in its brooch setting for over 130 years. This stone is one of the most celebrated diamonds in the Iranian Crown Jewels and it is also one of the oldest stones known to man.
De Beers Diamond
The De Beers weights 234.65 carats and is the seventh largest faceted diamond in the world. It was found in the De Beers Consolidated Mine in March 1888. Prior to being cut the diamond weighed 428.50 carats. It was centerpiece of a ceremonial necklace known as the Patiala Necklace in 1928. In 1973 the necklace disappeared and then the remnants was discovered in a jewelry shop in London in 1998 with most of the large stone missing. The De Beers Diamond was sold in 1982 for $3,160,000.
De Young Red Diamond
The De Young Red is a 5.03 carat red diamond and is considered as the third largest in the world. This diamond is not really pure red. This stone has a slightly brown hue which makes it look like a fine garnet that ruby-like. Since this diamond has very unique color, this was once sold at an estate sale as a red garnet. Luckily, this fine piece of precious stone was later on recovered and identified to be a very rare red diamond. At present, the De Young Red is under the custody of the Smithsonian Museum in Washington, DC and often figured in exhibits in that museum.
Unlike the Type I diamonds that derived their color from impurities imbedded in the diamond, Red diamonds are considered a Type II and get their color from a process known as Plastic Deformation. They get their coloration due to structural anomalies caused by Plastic Deformation during the crystal growth. The intense pressure changes the lattice structure of diamonds and has led to the formation of Pink, Red, and Brown colored diamonds.
The largest natural green diamond in the world is The Dresden Green. It is classified as an "apple-green" color and weighs in at 40.70 carats. The Gemmological Institute of America examined the stone in 1988. The Dresden Green Diamond was proved to be not only of extraordinary quality, but also a rare type IIa diamond and is consider the largest and finest natural green diamond ever found. The Dresden Green gets its name from the capitol of Saxony where it has been on display for more than 200 years. The earliest known reference to its existence occurs in The Post Boy, a London new-sheet of the 1700's. The diamond was sold in Switzerland in 1997 for $715,320.