IWC Mark XV Black Dial Difference?

My first post. I own a IWC Mark xv as does a friend of mine both identical watches but what appears to be a colour variation on the dials. Can anyone help. One is a rich Matt black. Like a deep black. The other a dull black bordering on black/grey. Could it be the glass which explains the variation? Shall post pics shortly when I've figured a way to do it

](www.imagebam.com/image/6b36b2486233863) [/img]

It looks like the one on the left has a AR coated saphire crystal while the other one has the older saphire crystal before IWC started using coated crystals.