I think G30 black is even being called G30 now. The G30 O Store London Gascans were G30, but had a black reflection.
Before G30 was a blueish mirror, but I'm assuming different than Blue Iridum, because there's Persimmon G30. If G30 iridium was blue, then there would be no need for HI Persimmon, which is Persimmon with Blue Iridium.