Grey invitations can really vary in appearance depending on how much grey is used in the design and how dark or light the shade. Here are some examples showing not only different color tones but also different ways of using grey as part of your elegant invitation design:
As shown below, you may even include silver as a shade of gray since both appear quite similar with the design below showing a silver invitation held on a black backer card with silver swirls.
This pocket style uses a lighter shade of grey for wrapping around the white invitation card. 
This unique selection ties the white invitation card to a gray colored base and you can also choose that same color shade for the imprint ink.
As always, these are just a very few examples of the grey wedding invitations that are available, especially if shopping online.