DIAMOND Perforating Tool -- from Pergamano. 

Pergamano Diamond Perforating tool is named after the shape of its tip.  The Diamond Tool has four flat sides that make you think of the shape of a cut diamond. Tool's needle fits exactly into the meshes of the netting of the Easy-Grid regular. This ensures the perforations are at equal distance from each other, resulting in a regular perforation pattern. (Dot illustration enlarged.)

Made in The Netherlands.
From Pergamano, The Netherlands