(IDEX Online) - Scientists have discovered the largest ever diamonds in outer space - and say they were formed by the enormous heat and pressure of planets colliding.They're convinced that they weren't produced deep beneath the surface of the planet, like diamonds found on Earth.Researchers at Goethe University, Frankfurt, Germany, found tiny extra-terrestrial diamonds, as well as graphite, inside meteorites - rock fragments from outer space that landed in Morocco and the Sudan.The diamonds are just a few tenths of a millimeter in size.The geoscientists concluded that they formed in the early period of our solar system, when minor planets collided together, or with large asteroids.They say their findings disprove an earlier theory that they originated deep inside planets.Professor Frank Brenker from the university's Department of Geosciences, said: "Our extensive new studies show that these unusual extra-terrestrial diamonds formed through the immense shock pressure that occurred when a large asteroid or even minor planet smashed into the surface of the ureilite parent body."It's by all means possible that it was precisely this enormous impact that ultimately led to the complete destruction of the minor planet."Pic courtesy NASA shows artist's concept of planets colliding