My friend and contractor Rod McLamb at Spyglass Building Company and I have been discussing pebble stone tiles from Costco, which run about half the price of our local tile shops. Since these tiles have a relatively wide grout joint, it’s important to choose the right grout color. Typically my experience is that a grout color that is darker than the pebbles will look better than a lighter color. A darker color will recede into the background and let you focus on the actual stones. When the grout is significantly lighter than the stones, it tends to accentuate their shape, and almost ‘flatten’ them, making them look slightly fake and ‘cheap’. Since the grout plays an important part in the appearance of stone pebbles, my recommendation is to have the tile setter create a sample prior to grouting the actual installed pebbles.