Ergonomic scissors are adjustable with respect to thumb offset, thumb ring rotation, and thumb/finger ring diameter, so as to enable effective control, in conjunction with unstrained wrist movements, of scissor roll, yaw and pitch. A set of interchangeable thumb rings of various inner diameters accommodate a range of anatomical thumb sizes. Each of the interchangeable thumb rings is rotatably attachable to the lower shank through multiple discrete placement openings in the bottom face of the lower shank.