New details have emerged about the surprise bankruptcy protection filing of GT Advanced Technologies, a.k.a. the company that was supplying Apple with its sapphire. As per the Wall Street Journal, Apple agreed to lend GT Advanced a total of $578 million to help get its large sapphire factory in Arizona up and running, only for Cupertino to withhold the final $139 million payment it was due to make, for reasons which aren’t yet clear, but likely relate to the company’s failure to deliver sapphire to Apple’s satisfaction.