Norma Decas - color difference

I have noticed when comapring multiple 2ml amps of Norma Deca that they color seems to be different (more yellow) in some amps. I was told that the discoloration is due to light. I know they're coming from the factory but am just curious of the different color.

it's common. i heard it due to slight variations in the colour of the oil.

Normas are great bro, I am using now. I haven't noticed the color change, but I also haven't looked that close at the color yet.