The physics of rising are described in a book I've owned for many decades, Classical Mechanics: A Modern Perspective, by Barger and Olsson. Here is their diagram.
The diagram shows friction, offset from the axis of rotation, being converted to rising torque by gyroscopic precession. Big balls rub the mirror farther from the axis of rotation for a given tilt angle.
In your case, I expect your teflon ball is flattened where it touches the mirror because it is soft. Although it's a low friction material, it's only moderately lower than your ruby (sapphire) which is hard and not flattened. So the flattened teflon rubs the mirror farther from the axis of rotation.
I'm sure that you've noticed that a point has no righting effect.
However, to the degree that a tilted top orbits, friction is reduced. Friction requires slip.
Best,
Alan