A newly observed white dwarf star may be the coldest ever discovered. The dead star is so cold, in fact, astronomers believe its carbon has crystalized, making it the largest diamond ever found -- about the same size as Earth.

Adding to its litany of superlatives, the diamond of a star is also one of the faintest ever discovered. It may sparkle up close, but it's invisible to humans. The only reason it was spotted is because it has a much more conspicuous orbital companion -- a pulsar formed from a supernova that emitted great streams of radio waves out into the cosmos.

The two stars are located in the constellation Aquarius and were found with the help of the National Radio Astronomy Observatory and its Green Bank Telescope in West Virginia.

"It's a really remarkable object," said astronomer David Kaplan, a professor at the University of Wisconsin-Milwaukee who led the study of the new diamond star. "These things should be out there, but because they are so dim they are very hard to find."

The discovery of the cold, crystalized star is detailed in the latest edition of the Astrophysical Journal.