Hi,
any LEDs that need 5V or more, incorporate a driver circuit. They are no longer LEDs.
I have never heard of a 1.2V LED.
Most LEDs are in the range 1.5V to 4V and need external current limiting.
You can easily measure the Vf using that test equipment.
Run @ 2mA and see how bright they are. Try 5mA and if it burns out then that was too much.