This graph shows the pressure and temperature stability fields for graphite and diamond, the polymorphs of carbon.
The vertical axis denotes pressure in gigapascals, from 0 at the bottom left, to 9 at the top left.
The horizontal axis denotes temperature in degrees Celsius from 0 at the bottom left to almost 4000 at the bottom right.
The stability fields for diamond and graphite are separated by a diagonal line running from 0 °C and 1.5 gigapascals on the left, to 2800 °C and 9 gigapascals on the right.
Diamond is stable above this line and graphite is stable below it.