Travertine is a natural stone tile. Since each tile is an individually cut piece of stone, chances are that there will be some variance with the shape, size and thickness of each piece of tile in an order. Luckily, travertine is a fairly soft and porous stone, allowing you some leeway when you need to grind it down due to level tiles. While the grinding of travertine is an easy task, the difficulty comes with the rehoning of it to match the rest of the floor. Do not be deterred, however, as the grinding of travertine tiles can be done by even novices at home improvement.
Find the spots on the travertine floor that need to be ground down. Mark those areas with a pencil, so that you know where the areas of concentration are.
Using an orbital sander, sand the areas which need to be ground down with coarse grit sandpaper--below 100 grit. Sand with the coarse grit sandpaper until the area is at the desired height.
Using an orbital sander, sand the areas which have just been sanded with medium grit sandpaper, between 100 and 220 grit. Sand the areas until you have removed the grit marks left by sanding with the coarse grit sandpaper.
Using an orbital sander, sand the areas which have just been sanded with fine grit sandpaper, above 220. Sand the areas until you have removed the grit marks left by sanding with the coarser grit sandpaper.
Using a cloth or mop, apply the tile and stone sealer to the travertine to give it an even shine. Reapply the sealer until you get the shine you desire.
If there is a large amount of grinding to be done on the travertine floor, consider renting an upright floor sander, which will sand large areas at a time evenly.