Can any pen be used on pearlescent invitations?

A pearlescent finish alone does not establish compatibility with every pen. Test the intended pen on the selected grade, writing side and finished area. Check line continuity, smearing after drying and transfer when cards are stacked. HALO is a white pearlescent material direction; writing suitability must be confirmed for the specific stock. Assess printed, foiled or otherwise treated areas separately. Keep the approved paper sample and pen model, and identify the writing area for the design and production teams. Repeat the trial if the paper, pen or process changes.