Cotton Rag Paper

Please help!!

I have a bride looking to letterpress her invitations. However, she received a sample from a company that had a "diamond pearlized" cotton rag. 

I've heard from some vendors that pearl cotton rag doesn't even exist. Rather, it is a cotton rag that has a varnish over it - and therefore not real cotton rag in its true sense. 

Has anybody dealt with pearlized cotton rag before, and if so - what vendor did you use to order it? Or are any of you a vendor/printer? I'm having one heck of a time obtaining this paper & I need to send her quotes! 

The printing will include invite & rsvp. 

Thank you!!

xo,

Kristina-Nicole