Unexpected Orange Colors

I took the photos below while photographing only ordinary drops of pure, clean water falling in front of a black featureless background. In the first set of photos we see some unexpected orange color.

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :

In the next photo we also see some unexpected orange color :