Advice... no probs, just trying to help you to make sure it lasts...
You will need to remove grout from the said tiles, this will make tile removal easier and stop damage to surround tiles from breakage shock..
Once up and cleaned out and then services installed and patched in with rapid setting cement.. then you can replace the tiles..
Use a CF2 adhesive and ensure solid bedding of the tile.. leave to dry for 24 hrs to ensure moisture from the stone.. then seal with a suitable impregnator.. leave to dry... then grout and clean down when set enough..
Make sure the tiles are clean and leave to dry for min 24 hrs.. then seal again with enough coats to the point of saturation.. but making sure sealer does not dry on the surface... leave to dry and make sure that the tiles are kept dry for 72 hrs to allow sealer to fully cure.