There is a Jony Ive Edition film about the gold that was not shown at the event. He describes the process and it's not a ceramic alloy. It is a traditional gold copper, palladium and silver alloy. The BIG difference is gold is usually cast into the design. Apple is instead casting ingots, pressing them to remove any pores and then machining the gold case. This would create a stronger finished product but potentially more waist/expense. Of course at $10,000 and up cost is no a factor.