nah, i'm pretty sure back in my day blue meant "homogenised" which meant it was blended hard so it emulsified. the gold caps they had a chunk of cream/butter at the top of them and would accrete that over the few days after it was delivered.

then there was skim, i forget what color. red maybe. it was basically the gold with a mechanical filter to remove the solid cream out of it.

idk how "skim" became normal. but it had something to do with selling palm oil, or sunflower oil, or chemically extracted olive oil.