Toroid core types by color ID?

[FuZZ1L0G1C]

Hi. What does the color signify on toroidal cores?
As most articles I've seen so far don't list this specifically, but do mention certain cores such as compressed ferrite having different magnetic permeabilities between the material types.
So I wonder if color = "core material" code?
At first I thought it was frequency range application, such as for LF mains power, audio, RF, etc.
However, this would be too broad-spectrum for selecting a specific value.
For example, I have several dozen cores of varying sizes, cross-sectional shapes and colors floating around at home, some from components bought long ago for un-built projects, other stripped from old equipment.
Thanks. Clive.

 

[Harald Kapp]

As far as I know color is not used for coding any particular property of toroidal cores.

 

[WHONOES]

Some do. I still have some colour coded cores. Unfortunately I can't remember who the manufacturer is / was. If I do, I will come back.