Brian -

The ferrite toroidal cores have no orientation preference. Depending on the brand, the color is most likely an identfication mark. The core idenification indicates, among other things, it's characteristics such as inductance per turn, saturation limits, effective frequency range, etc. In use, these inductors see an alternating current (AC) - admittedly, at radio frequencies (RF) - but AC nonetheless, so they look the same to the signal in either direction.

Regards,

Dan Schaefer
(LNC2 driver and retired Electronics Engineer who spent many years designing such magnetic components.) --
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