Four "tricks" to overcome a recalcitrant lid.
Hang a kitchen glove (silicone type) to hold the lid firmly.
Apply continuous pressure, turning counterclockwise.
Engage the blade of a screwdriver or round knife between the metal of the lid and the glass of the jar.
Exercise a slight twist to allow air to return.
Immerse the jar for a few minutes in boiling water to increase the volume of air inside and reduce the pressure of the lid on the glass.
As a last resort, pierce the lid with an oyster knife held upright, giving a sharp blow to the handle.
Another method is to turn the pot upside down and apply a sharp blow with the dish of
hand on the bottom of the jar.