That isn't the real name.
It is a diagram where the y axis is radius on a logarithmic scale, and x axis is bulk density on a linear scale, published in a document [ http://www.boulder.swri.edu/~hal/PDF/planet_def.pdf
] in 2000.
I think I may have discovered something important on the graph...
There are TWO distinct bands that I have found. Looking at the key, you can note one band is the gas giants, and one contains they rocky planets. Where the bands meet, you find the icy objects... That's just it...
Red = gas
Orange = Rock
Blue = ice