Diamond planets?

Some planets in our galaxy could harbor an unexpected treasure: a thick layer of diamonds hiding under the surface, astronomers reported on Feb. 7, 2005. No diamond planet exists in our solar system, but some planets orbiting other stars in the Milky Way might have enough carbon to produce a diamond layer, Princeton University astronomer Marc Kuchner said in a telephone news conference.

In gas with extra carbon or too little oxygen, carbon compounds like carbides and graphite could form instead of silicates, Kuchner said at a conference on extrasolar planets in Aspen, Colorado.

[and maybe buckyballs and fullerenes, too?]