Cleaning travertine tiles

[pagi]

We got a great deal on some travertine floor tiles for the kitchen and I really looked forward to my lovely floor. However, the builder who laid them never sealed them properly so the are getting holes in them where they are wearing away. We need to clean the floor really, really well and reseal it, but I'm unsure what I can clean it with. I don't want to damage the tiles.

My collie has walked lots of mud over the tiles so they do need some serious TLC. Just hot water isn't doing the trick.

Any ideas? I can't afford to ruin this floor!

I don't think that's a problem with the sealing. Ours do that too and it's because travertine naturally has holes through it. When the tiles are cut they seem smooth but as they are walked on a thin top layer is crushed and the hole appears. We fill ours with beige grout

call a stone flooring co. someone will be able to tell you what products to use etc.
i do think the holes will need filling, like modernart says - you can colour the filler to blend as well as possible with the particular bit of stone the hole is in... or you can get coloured grout. speak to a decorators suppilers.