(a) certification

[HolyUnicorn]

Hello,

I gained (a) certification in scuba diving. (Self-made sentence)

My intended meaning is I was certified to do scuba diving.

Is “a” needed here? I checked dictionaries and "certification" can be both countable and non-countable.

 

[Barque]

You could write it with or without "a" but a more natural way of saying it would be "I'm a certified scuba diver".