Carving...

...is a particular set of reliefs...

It is the manual embossing by cold hammering that was adopted in the workshop. 

Hammering of various stamps and chisels, on vegetable tanned leather exclusively, which allows the contours of a design to be lowered and textured, by creating a play of reliefs which is similar to an augmented 2D ... 
A sort of inverted version of engraving, that digs the motif into the material ... and a slow, precise and technical practice which does not admit of error! 

Embossing can be completed on the back to give more volume ... and tinted in various ways to accentuate the effects.