oh yeah I meant graphite >.> Sorry :(
Ok here goes.
Apparently in 2005 a group of german physicist found that by compressing Fullerene molecules, (according to wikia this is about 60 carbon atoms per molecule. I haven't found a supporting source for this though..albeit my head has been turned by the ADNR's
) to a pressure of about 20 GPa (this is confirmed else site) and at the same time heating it to about 2500 kelvins, a new substance called Aggregated Diamond Nanorods (ADNR)
This substance was compared to a crystalline diamond by loading a diamond anvil cell with both single crystal diamond and ADNR material, in order to directly compare their behaviour under static load. It was found that through this, the ADNR was 11% more compressed when compared to the crystalline diamond (will post link to my source so you can have all the nifty equations) Experiments conducted at the ESRF confirmed that the X-ray density of the ADNR material is higher than that of diamond by 0.2 - 0.4%, thus making it the densest form of carbon.
That being said. I could not find any supporting facts about the color of the ADNR, however I did find an interesting pic of Stereomicroscopy of the ADNR here http://www.esrf.eu/news/spotlight/spotlight25nanorods/spot25fig1
However, considering the density, and the heating that occurs during the creation process I would assume it would be black or close to it, as the interconnecting diamond rods would give it a denser look..what looks more dense then black? *shrugs*..this is just a wild stab inthe dark
Though the Stereomicroscopy picture makes it look a bit multi-colored. http://www.esrf.eu/news/spotlight/spotlight25nanorods/index_html/