A previous review of these knobs on Wayfair mentioned an issue with the glass knob breaking away from the metal stem.  Other reviews didn't mention this problem, so I went ahead and ordered eight of them.  Once they were installed on small cabinet doors, the first time I opened one, the glass portion of the knob fell off in my hand.  I have twice hot glued it back into place twice but, when used, the knob still falls off.  We are now afraid to use any of the other seven knobs; luckily, the cabinets can be opened using fingertips at the side of the cabinet door.  We now have larger-than-normal holes in the doors to accommodate the 'stem', so it will be almost impossible to replace the knobs with a standard knob.