It’s sort of funny how we think of colors associated with invisible things.

I just read a chinese proverb about an ‘invisible red thread’ that connects people.

Does indicate that we often think of invisible things as simply hidden? Not inherently having the quality of invisibleness, but merely masking the true color of the object?

And yet we have things like glass and plastics which can be clear, or transparent, despite not being invisible persay. What about really clean, glare free glass, do we ever consider that invisible? I mean, I’m sure it’s marketed that way, but do we think of it having the property of invisibility, or merely blending in, or letting light through.

The actual criteria for invisibility would be interesting to look at, if there are any. Does something that bends light around itself count? If so, it could still theoretically be colored, and possibly viewed from some angles that reveal that color.