"... A lot of times, when this discussion comes up about sealing granite, I'll refer people to a page in that site that has links for two sets of tables-- one A-L, and the other, M-Z, listing the names of the more common "granites". One of the things they list on those pages is the absorption rate of each stone, and anything with less than a .25% absorption rate should NOT be sealed. ..."

Granite lists - Explanation

Granite lists on findstone.com - Table A - L

Granite lists on findstone.com - Table M - Z

However, for any stone you can check for the need for sealing by doing the "sponge test"...

Again, from Bill Vincent (Mon, Mar 9, 09 at 13:32)

"... the "sponge" test. That is, to drop a sopping wet sponge or rag on the stone, and allow it to sit for a couple of minutes. You then remove the sponge and wipe up any water left on the stone. If it leaves a dark mark, you'll need to seal it. ..."

Another way to tell is if water beads up on the surface. If it does, it probably does not need sealing. But I would do the "Sponge Test" to be sure.

BTW...have you read the stone information in the "Read Me" thread as well as the information linked from the "Read Me" thread? I highly recommend all stones be tested prior to purchasing so you know exactly what you're getting...not just the need for sealing against stains, but also how likely it is to etch, whether it's dyed (for black granites, primarily), etc.

What did your installer say to do? I just posted this
note to Shilosmom on the decorating forum. Maybe it can
help you too.

--------------

Hi Shilohsmom,

Normally granite is sealed at the factory but should still
be sealed once installed in your home.

I have Virginia Jet Mist honed granite that is known to be
a bulletproof granite. Statues and monuments are made of
this stuff. But, I still needed to seal it. I used SCI
from Homedepot. It came in a spray bottle. I think SCI (no
not csi ) stands for stone care international. Some brand
I am sure.

My installer told me I had to wash the counters and not
touch them for 24 hours. Then spray the sealer not over
saturate but enough that you want to wipe it down but
DON't. Let it sit 10 minutes and then spary again. After
30 minutes then I could dry the excess with a soft dish
towel.

There are also directions on the sealer products that you
might find at any hardware store.

My installer recommended I seal my counters once a year.
I know people who do it less. My neighbor has Ubatuba and
has never sealed their counters. They have had them for
10 years. I am not recommending this, just saying I think
some people do and some don't.

I have a family that is clumbsy and is known to spill
Vinegar, Oil, Lemon, Red wine (does not show on my
granite), melted butter, melted cheese, amd a host of
other products that could ruin a counter.
So sealing my countertop is really important for the life
of my kitchen.

Why should I be concerned about oil on the counter? Well
oil will eventually evaporate from the stone but it takes
time. Imagine spilling some car oil onto the driveway.
Yuck. right? Well I don't want olive, peanut, safflower,
corn, veggie or any oil to stain my rock. Even smeared
buuter. So Sealing can help protect the stone. What about
vinegar or wine? Acids can also effect stones. They
can slowly etch away. Especially a honed surface.

I hope this helps. If not check out those links and maybe
they can help you too.
~boxerpups

Oh dear, I remember someone having a white ghostly haze
appearance to their counters from OVER sealing. This is not
good either. Check out that link. Not to scare you just
to inform you.

Granite was sealed and has haze HELP
http://dir.thathomesite.com/forums/load/kitchbath/msg061752031423.html ?10

About Sealing Granite counters

http://homerenovations.about.com/od/kitchens/f/sealgranite.htm

How to Seal granite from EHow

http://www.ehow.com/how_2106339_seal-granite-countertop.html

Granite Sealer a different product that what I used
http://www.marble-cleaning-products.com/granite-care-products-granite- sealer-c-68_63.html

Here is a link that might be useful: Sealing Granite

NOT all granites require sealing.

If you seal one that does not absorb the sealer forms a film on the surface of the stone and will quickly look splotchy and uneven as it wears away from normal use and cleaning.