The above answer is correct -- an enhancing sealer will darken the stone but otherwise should not. Even so, I would test any sealer on a sample of the material before using it in the installation just to make sure.

Thanks. I'll ask the contractor for a little bit of sealer before I commit to the stone.

I was just about to suggest what lascatx said. But, in your reply you said you were going to ask your contractor for a little bit of sealer. Keep in mind there are different kinds/brands of sealer. Just because his may make your sample darker doesn't mean that there isn't one out there that would work. We used a sealer on our Botticino marble backsplash, and it didn't change the colour at all.

A good tile place should have various kinds of sealer, not sure if they would be willing to let you try them if you brought your sample in...but that could be another option for you.

Just because I'm nosy, and love to see what everyone else is doing, do you have a pic of your porcelain tile, and how do you plan to use the mosaic?

Thanks, raehelen. I don't have a pic yet -- still working off the sample boards from the tile shop. It is time to choose between Emil Ceramica Keystone Fire or Cliffside in beige bluff (maker unknown, but distributed by Florida Tile). The mosaic is a tumbled travertine 1x1 from Home Depot. It goes well with either tile choice ... when it's dry.

Here's a link to a poor picture or two of Cliffside; Keystone link below:

http://www.floridatile.com/products/cliffside

Considerations for Keystone:
Wonderful movement (but may be rather busy for a small room)
Comes in a wider variety of sizes, including 6x6 and various trim pieces, so we could use 12x12 on the floor and 6x6 on the wall
But it's slightly darker and slightly more expensive.

Considerations for Cliffside:
Very nice texture, almost like sand
There are no good installation pictures available
Its smallest size is 12x12, so we'd use 18x18 on the floor, set diagonally, and 12x12 on the wall. I don't think bullnose is available, so we'll have to figure out something for that.

Vanity is Magickwoods Sonata; fixtures are chrome. Sconces are Avia from Restoration Hardware.

Our home is out in the woods in New England. I'm hoping for a rustic Zen sort of look -- originally wanted tumbled slate, but this room gets no natural light, so my husband nixed that. So I proposed tumbled noce travertine and he felt it was still too dark. My husband wants white tile, but I'm adamantly against it, unless we go with really expensive handmade tile, and he's adamantly against that.

This is a very occasional use guest bathroom.

Here is a link that might be useful: link to Keystone Fire

I like both. Found an installation pic of the Cliffside (I find doing a Google Image search best way to find these kind of pics)

Did you say what your countertop was? We must have very similar tastes. I love slate too, and considered Travertine, but DH nixed real stone cuz of upkeep issues. If your counter is at all busy, the Cliffside may be a better choice. I ended up choosing a limestone looking porcelain tile for our floor and shower walls.

Raehelen, thanks for that picture of the installation. The vanity top is one big white porcelain sink, so we could go either way. I'm leaning toward the Cliffside, because the color is a little warmer. And also because my husband likes it better! He nixed natural stone, too.

I put Dupont Bulletproof sealer on white marble floors and counter tops (both polished and honed) and noticed no difference in color.

Thanks, Tim. Did it change the shine on the honed surface?