As it turns out, there is indeed a diamond too large to make an appearance on "Pawn Stars" and too heavy to be cut and polished for a pendant necklace that will eventually fall into the hands of celebrity royals.
In August 2011, astronomers discovered a celestial body that's essentially a giant gemstone orbiting a nearby star. Scientists suspect the 'planet' is actually the remains of a star whose gasses fused, during its high-pressure, super-heated death, into crystallized carbon -- otherwise known as diamond. It also probably contains lesser amounts of oxygen near its surface. (Learn more about How a Supernova Works.)