To restore shine on natural stone tiles, you should follow the following steps:- Take 1/2 bucket of warm water. Add 1 to 2 squirts of liquid detergent into the bucket. Scrub the stones using soft bristle brush. After scrubbing, rinse the tiles with clean water. Let it dry. After its completely dry, apply an even coat of high-gloss penetrating stone sealer (easily available on amazon) using fine-bristle paintbrush. If the stone is exceptionally smooth, use a lint-free rag and wipe it instead of brushing. Repeat the step 6 for additional coat of the sealer (Follow the manufacturer's recommendation).