When, if and (http://maplered.com) what sealer?

Hello.

I need your help. I just had my Counter (http://GialloFiorito.com) tops installed, the guys that did the work say it does not need to be sealed. Everyone I speak with says it does.

As I started looking into this I have discovered a dozen different types of sealers. Why would my Counter (http://GialloFiorito.com) top guy say this. They did a nice job. I just feel like the job is not finished.

Any advice would be appreciated,

Joan T.