Warning: ACTUAL PHYSICS, not typical Slashdot half-assed speculation...
Calling this a diamond is simply wrong. Perhaps at some point in the distant future one of these will cool and part of it will become a form of crystal carbon, but considering that the cooling time without mantle carbon crystallization is on the order of 10 Gigayears, it is not likely this has happened yet considering that the universe is around 13.6 gigayears old...
OP here. Not claiming to know much about this; I just pointed out the NRAO announcement. But I assume that NRAO does have people that know something about the physics here.
They are not saying that the white dwarf is 3000 K - they would have detected it directly then. They are saying that it must be cooler than that, perhaps much cooler. Thus, they are speculating that this is an extremely old object, and that it may indeed have cooled enough to reach temperatures at which there would be carbon crystallization.
The Tao is like a glob pattern: used but never used up. It is like the extern void: filled with infinite possibilities.