MAPEI's Keracolor U grout is unsanded. So, it's a great choice for grouting most installations of glossy wall tile. Other good options are Ultracolor Plus FA grout and Ultracolor Plus Max grout. When grouting installations of antique or handmade wall tile, it is recommended to build a mockup (sample board) or, at the very least, test these products in an inconspicuous area before grouting.
Cement-based grouts have been around for decades and are very reliable, but are also the most porous and stain-susceptible of all the grouts. Instead of using just plain water to mix the grout, use MAPEI’s UltraCare Grout Maximizer, a water-based additive for grout that fortifies the flexibility and stain resistance of the grout.