It's difficult to see The Spaniels after dark. There's a lot of space in the fields where we walk them. I have reflective collars on them, but light has to hit those just right for them to reflect anything.
We're trying the Nite Ize NiteHowl LED collars. They're much more substantial than they look in photos. Those tubes are solid and feel durable. They plug very securely into a short silicon tube with a light in it. The collars do slide right on and off of The Spaniels, and those spaniel ears hold the LED collars securely in place. It would be easy to pop one end off and reconnect it if the collar needed to be too small to go around the face easily. (I don't know if that would eventually wear out.)
We can see the lights from across a 2 acre field. It's about 200 yards (~180 m) to the far end, and we can always tell where they are in the field. Under the porch light or the flashlight they're more visible with the LED collar.
I have had these collars 3 days and they're already indispensable. And look, even the "pretty necklace" trick has a practical use. Much like science, when pure science research is frequently done just to see what the results are... once it's complete, sometimes there are surprising applications.