Here's another recent trend that highlights the illusory nature of the diamond market. By far the most common color among mined diamonds is brown, which are even more common than colorless stones. Only the colors pink, green, blue and red are truly valued in diamonds. Due to their excess supply and the perceived lack of appeal in that shade, brown diamonds sell for much less than other "fancy," or colored diamonds. They are usually directed toward the industrial diamond market, where they sell for a fraction of the price.