Patching and Plastering - Grout sealer/Tile finish?

I built an Arts&Crafts style coffee table. The tabletop is tiled with thick unpolished green marble. The marble tile is rough, with some cracks and veins of white and black. I used white grout. It looks very nice, but now I wish the tile were darker and deeper in color. When I wipe it with a damp cloth, the difference is stunning.

I wonder if there is a product I can use to give it a wetter look without leaving a plastic-like coating. I do plan to seal the grout, of course, and I've heard differing opinions on applying sealer. Some say I should apply it with a syringe, or otherwise take pains to apply it only to the grout. I've also heard that it's okay to just paint it on without regard. I would be tickled if grout sealer, painted on liberally, would do the job. I'm sure it depends on the type of tile, and this tile is of course very porous.

Thanks a bunch!

Rip

I used grout sealer to seal unglazed terracotta tiles in an entry hall. Worked just fine. With marble, I suggest you talk to a pro first. There may be something special for marble.

All natural stone products should be kept sealed and cleaned and maintained only with recommended products for stone. Marble is absorbent and is subject to oil and other stains, particicularly acid stains caused by drinks like juice which contain citric acid.

http://www.stonecare.com/shop/browse/a5db2c7e16865a1bf6b6f36a1ccb76d3?ps_session=0fa6572cda7e0baad6ecd5343077d20e