IN general, I like to keep cool tones and warms tones together. Your beige is probably a warm tone, the gray can be cool or warm, depending, it may clash. Grays and brown tones (beiges) also tend to not mix well in some instances. t may also make the beige appear "dirty". Not sure, see if you can get a fabric swatch or a pillow and place it against the wall. Look at it in day and night light. If you like it, then its your house.