Revenue stamp dating
The ink could be of different colors for different purposes.However, parchment (vellum or skins) was used for many important legal documents because of its durable properties.
Only a few examples of white base paper (unlinked) are known, from 1694-95.
From 1694, there was a clear distinction between the techniques for stamping paper and parchment.
Embossing on paper was quite straightforward, at first uncolored and then, from about 1883, often with dies that could both emboss and ink simultaneously.
Again, colored inks were used for special purposes. Indeed, quite often where one value was needed for a different purpose a new die would be prepared.
Pink was used as above, to be replaced by blue ink from 1902. For the semi-adhesives on blue paper it is possible to collect over 150 different values The many values, and many dies for each value, make the total number of collectible dies quite formidable.
So from 1701 security was improved by making a small double slit through the parchment with paper attached, passing a thin strip of metal right through, bending it over and then holding it in place by gumming on a square of paper (2.2 cm x 2.5 cm) called a cipher seal.