"It depends when they bought it and what you compare it with"
Exactly now you get my somewhat obvious point.
Of course I don't know when central banks bought their gold and at what prices. I assume for many they may have been bought 80 years ago. I also do not know at what price they bought and at what price their currency was at at the time of purchase. That's probably why I correct stupid statements about central banks buying gold rather than making them.