I am a tile setter.

“Miracle 511 Impregnator” is an excellent sealer.
I recently used travertine for my kitchen counter tops and sealed it with this product.
It is a bit pricey but well worth it.

It comes in various sizes .

A quart will cover 250-1000 sq ft. Depending on the type of tile your trying to cover.
The container is blue with a yellow lid.

Hope this helps

I ve used both the Miricle 511 (good but pricey as said) but also Ceramaseal, (sp?) Comes in a green bottle . Get it at HD for about $30 a qt
I ve used that on most all my natural stones before and after setting and never a problem GL

Use Dupont Stonetech Bulletproof Sealer, if you do not want to change the look of the tile. Apply at least two coats. If a heavy traffic area, apply three coats.

You will need to reseal in 2-3 years if not a high traffic area. If high traffic area, you will need to reseal in 1-2 years.

Down the road, you will know by testing a little area by dropping just a little water on it. If it beads up and sets there for a moment or two, it won’t need to be resealed just yet. If the water immediately absorbs into the tile, then it needs to be resealed.