Can I omit "which"+verb in a non-defining relative clause?

Which sentence below sounds better? Is there an incorrect/correct one? Is there a difference in meaning?
I tend to like the second one the most. To me, it has the same meaning as the first one but bit fancier, idk 😛

1. The NIR had just been discovered: a type of radiation undetectable by the human eye.
2. The NIR had just been discovered, a type of radiation undetectable by the human eye.
3. The NIR had just been discovered, which is a type of radiation undetectable by the human eye.