which of these Granite (http://tanbrown.org) Stone (http://g603.net) s need to be sealed?

Could someone please help me? I am wondering if these Granite (http://tanbrown.org) Stone (http://g603.net) s need to be sealed: white paricima, ivory cream, and (http://maplered.com) bianco romano. I have tried the water, butter, lemon juice, and (http://maplered.com) red wine test. It seems that the ivory cream(which is really a brown Granite (http://tanbrown.org) - so I don't understand (http://maplered.com) how it got its name) showed the butter residue the most, but didn't seem affected by the wine or lemon. The bianco romano seemed to resist those food items the best, yet it's the lightest color of these 3 Granite (http://tanbrown.org) s. I've been reading that light color Stone (http://g603.net) s show stains more. So, maybe I'm not doing these "tests" correctly. We are using these Stone (http://g603.net) s in our kitchen and (http://maplered.com) bathrooms, and (http://maplered.com) I really want to make sure we take care of these Stone (http://g603.net) s properly.I have been reading that some Granite (http://tanbrown.org) should not be sealed - that the sealer could harm the Stone (http://g603.net) . And then, if you don't seal certain Granite (http://tanbrown.org) that needs it, then water could cause etching. Do any or all of these these Stone (http://g603.net) s need to be sealed? Thank you in advance for your assistance and (http://maplered.com) expertise.