A mint stamp with original gum that has not been mounted or hinged.
A mint stamp that has previously been mounted or hinged, normally with some hinge trace or disturbance to the gum.
The Stanley Gibbons catalogue reference used to identify and catalogue stamps.
The catalogue value quoted from Stanley Gibbons. It is not the same as the UPA auction estimate or a guaranteed selling price.
An abbreviation for watermark: a design or pattern incorporated into the stamp paper during manufacture.