Mosaic floor polishing- What to use
Your first mistake was using the diamond pads. Part of the discoloration is stone dust being embedded in the concrete filler. You had a mold problem or staining from food/drinks being spilled. You should have started out with a non abrasive concrete / grout cleaner. You could have even used a mixture of beach and water. Try doing this and just work on the cement/grout filling. Once that's cleaned up use a buffing pad and polish on the affected stones.