Help identify refrigerant

Can any body help?
I found a full cylinder of refrigerant in my late fathers greenhouse the sun has bleached the markings and colour from the cylinder. It is a refillable type with 2 valves ect. the only clue i have is if i turn the cylider upside down the base looks to be pink in colour I think it may be r12 or 134a it may date back to the 90's
I dont have a ref identifier, what other way can i determine the contents! any detectives out there?
its a small cylinder 9Kgs i think but i would have to check. I thought of using pressure temp chart but how would i do this? any help:confused:

Pink was R502. If its a two valve bottle without check valves in it could have been refilled with anything.

Yes monkey spanners the cylinder would have originally been R502.
Testing
Take temperature of bottle or ambient if stable, measure pressure inside bottle then compare with PT chart. Ensure there is some liquid in the bottle when you shake it around.

If it was used as a recovery cylinder it could be any Refigerant or even a mixture of different refrigerants recovered out of different systems...

I will try to check this weekend etc