These were taken with a Cokin P170 red-green polarizing filter. Turn it one way it’s red, turn it the other and it’s green, turn it 90° and it reacts like a polarizer*. I love them so much I get them when I find them on sale and I don’t even have the proper holder.

*if you’re a photographer and you don’t know what that is you need to get educated and probably get one.