The inked impressions of hand carved stamps are generally 2-dementional. Giving 3-dementional appearance to the stamped images is a challenge for stamp carvers, but developing inking technique to add gradations to the ink is one of the solutions.
This is how I do it.
Preparing wet paper towel, crumpled small Kleenex ball and a peace of Kleenex.
Making a pad with the Kleenex ball and a peace of Kleenex.
Appling ink to the stamp. Wetting the pad and taking some ink off the stamp by tapping motions. This is how the image looks like. Cleaning the stamp with wet paper towel. I tried with lighter ink to show more transparency of the glass bowl, but the impression was too weak. So, I added darker ink to the top and bottom of the stamp. Added a goldfish in the bowl.