Bismihi ta'ala
I have read about the positive benefits of black aqiq stone, but not from our Islamic heritage. As far as the highly recommended and very mustahab stone that should be worn, it is the red aqiq. They usually refer to this 'red aqiq' as a aqiq kabadi, which means liver colour aqiq.
That would be the best ring to get, with this specific colour.
With prayers for your success.