Red is by far the rarest of all coloured diamonds. Less than 20 stones have so far been certified as red diamond. Some of the red diamonds have fetched more than million dollars per carat. Most of the other coloured diamonds fetch between five to six figures per carat.

Red is undoubtedly the rarest coloured diamond. Besides a 0.95 carat red diamond sold at auction in 1987 for over a million dollars, only a few others are known to exist. A 0.25 carat red oval sold a few years ago at Christie's for $326,800 per carat. Red diamonds are almost priceless.

Common names for red diamonds include blood red, ruby, magenta, raspberry, rose, strawberry, cherry, tomato etc.

Red diamond rough is mined in Australia, Brazil and South Africa.

Crystal lattice defects showing stress lamination during the formation of diamond causes red colour.

The most famous red diamond is the Moussaieff Red Diamond.

The secondary hues and colour modifiers include pink, purple, brown, orange, gray etc.

Enhanced red diamonds can easily be separated from natural ones due to their blackish overtones. They also lack graining and the distinctive absorption patterns of natural red diamond