If you're concerned that sealing it won't be enough, change your tile selection.

Sealing the stone is definitely a great choice! But you have to be aware that with natural stones there is more maintenance involved than a porcelain or a ceramic tile. If natural stone is the look you want, it definitely is worth the extra love and care! The best thing to do if and when small stains splash onto your stone, is to blot it with a damp rag. Do not use any harsh cleaning products. Water is your best option! You may want to reseal it a few years down the road to continue protecting it. Best of luck with your backsplash. It sounds like it is going to be gorgeous!! :)