discs for angle grinders

["tracy powell" <powells@zzzzzzz>]

Hi Norman,
Well it all depends on the function, whether you want to cut, grind to shape, or grind to finish.  Generally the discs come in 3 forms, saw blades, cup wheels, and combination discs, and these also can be divided into materials, diamond, silicon carbide, and aluminum oxide.
For soft stones, anything up thru soft marbles, aluminum oxide combination discs, the inexpensive "masonry" discs found in hardware stores, will both cut and grind to shape.  They usually only come in one grit, fairly coarse.  For finishing you can use aluminum oxide sandpaper discs on rubber backing pads, in all the grits usually found in sandpaper, but for this you need a slower speed, so either a second grinder or a variable speed.
The cup wheels, usually in silicon carbide, will grind to shape in coarser grits, and grind to finish in finer grits, and these will also work on harder stones, like granite and basalt, although they wear down rapidly.
Diamonds come in both cup wheels and saw blades, and will grind to shape, and cut respectively, any stone, including granite, basalt, jade, etc.  And of course there are way too many products to choose from.  Personally speaking, I like turbo blades in 5" and 7", and in the granite I find here, the most expensive blades seem to last the longest.  Continuous rim blades seem to cut cleaner edges, and are made for ceramic tile more than stone.  Segmented blades may work better in some stones.  If you are ordering these things from b-b or other catalogs, you should call them and ask what they recommend for which application.
Diamond cup wheels seem to be much more cost efficient than silicon carbide, and they can be had in 3 different grits, so will both grind to shape and first step finish.
All the diamond blades, wheels, and discs will cut soft stones too, and with proper care will almost last forever if that's all you use them on.  These gadgets all have their counterparts in the die grinder category too, but that's another conversation.
And please keep that dust mask on.
good luck,

tracy powell
http://www.powellstudios.com