(YouTube clip by MasikBon Origami Paper Crafts)
So. What color is that diamond-shaped piece of paper?
Give up? The secret is revealed below:
Mightly Optical Illusions revealed the secret: The diamonds are actually a gradient of gray colors - the top part of the diamond is slightly darker than the bottom part. Each diamond is exactly the same - even though to our eyes, the top row is darker than each of the rows below it.
Don't believe us? We drew in a white line to separate out the diamonds below.
These are still the same diamonds, except that they no longer touch their adjacent neighbors and our eyes are able to see the color gradients much more clearly - and the fact that they're all the same colors.
Neat, huh?
There is also a moire pattern glimpsed on the diamond at various points in the video as it's moved around, presumably caused by some sort of lenticular coating interacting with the pixel layout of the camera sensor chip.