I've been approached to do some work for a cemetery and they are quite excited about the possibility of using plates like these for the project. In my searches I learned something interesting about Czech cemeteries. The plots and crypts are rented by the families of the deceased and when there is no more family or if they stop paying rent the plot is often rented to someone else and often the headstone is reused and the plate glass is covered or replaced with a new plate. I find that a bit sad as it obliterates a lot of genealogical information, but it explains the reasoning for all the etched black glass plates. I had simply put it down to glass being a native and traditional material.
Where would a person start to source black glass and what would a reasonable thickness be for a 30" x 36" panel?
If I were to leaf some of the sandblasted text, are there any foreseeable problems in blasting, cleaning, sizing, leafing and then removing the mask and touching up any rough edges right away?
I also found a link to a glass monument place which I thought might relate to a post that was posted by Eric a while back. You may have come across this or perhaps someone else posted it before Eric, but if not you will likely find it a bit interesting, especially since our trip.

I've edited the title to add the word Vitrolite to help for future searches.