Polishing glass mosaic, advice needed please.

[Old Mod]

I want to change the shape of some glass mosaic and I've been using 60 grit stone polishing paper. It's working but it's quite slow and destroys the pads fairly quickly. Is there a specific polishing pad out there for this purpose does anyone know? It's not to polish the face, but the sides, so I can change the dimensions.
Any ideas?
Thanks.

 

[The D]

I use a granite grinding disc the type with the triangle segments. Try stonetools.co.uk or ATS