Do I have to use diamonds to hone marble? Are there any alternative materials?

Diamonds are the most popular abrasive for honing marble but are not the only abrasive. Alternative abrasives are as follows:
SCREENS screens are silicon carbide mesh that can be used dry or wet. The disadvantage with screens are that they wear very fast and do not last as long as diamonds. The advantage is that they are very inexpensive and unlike diamonds they can be used dry.
BRICKS Bricks are silicon carbide molded with a cement or polyester. Bricks are still used today at fabrication shops to hone and polish marble. The disadvantage is that they require a higher degree of skill to use. The advantage is they are inexpensive.
SANDPAPER Yes even sandpaper can be used to hone marble and is still used today by many fabricators for working edges of marble. The disadvantages and advantages are the same as for screens.