1: sunrise
2: sunset
3: sunset
4: sunset
5: sunrise
6: sunset
You can usually tell by the amount of particulate matter in the air. I mean there's a lot more smog at the end of the day than at the beginning, and it's the smog that radically alters the sun's color.
Numbers 1 and 5 seem more 'pink' whilst 2, 3, 4 and 6 look more 'orange'.