> sometimes light blue and dark blue are two different colours

I believe it's so in russian

> some languages consider pink to just be lighter red

This is interesting. Here in the UK pink is generally described and accepted as light red, but I've always considered it to be a separate colour, and I met someone who mentioned he though the same, so it's not just me.

There's light red but to my eyes that is qualitatively different to this https://www.macmillandictionary.com/dictionary/british/shock...

Any other views? Perhaps someone with knowledge of chromatics can better resolve the question.

thanks