Andy:
It's a smoked or tinted glass that is tempered.
The problem is getting it cut and the edges precision ground off.
Most glass cutters I know use a diamond tip cutter and then grind of the edges. This is great for glass tables and shelves but doesn't quite fit the bill for B&O.
If you can find someone to cut the glass properly then it is not hard make a replacement.
Mask off the areas where the digits go. The lettering can be made by using a laser printer on film (Black background with white font; the lettering will come out transparent).
Cut the film and glue it on the glass at the appropriate location. Then spray the entire back of the glass with black paint.
Finally glue the panel to the metal bracket.
The only thing that prevents this from being perfect is getting the nice edge on the glass.
If you can figure out/find someone who can do this we've got near perfect replacment panels!
Derek