Try looking at these threads...they appear to have some information.

http://ths.gardenweb.com/forums/load/kitchbath/msg091310171907.html

http://ths.gardenweb.com/forums/load/kitchbath/msg1213183711789.html

http://ths.gardenweb.com/forums/load/kitchbath/msg0917554319271.html

First of all: don't do what this thread did :http://ths.gardenweb.com/forums/load/kitchbath/msg091310171907.html

I will try to explain stains the best that I am able:
granite comes from the "factor" with a resin or (The polyester resin has also the added value of fast drying time, making it a perfect solution for automatic line manufacturing.)(Nowadays there are many different kinds of polyester resins, with different viscosity, color and hardening times. Some resins have even the capability of UV hardening, allowing a very fast curing time.)(Granite is much harder, with microscopic fissures and a different absorption rate. The very thin cracks represent an additional problem, since no polyester resin would have the capability to deeply penetrate in the stone, harden up and give a sufficient strength to the material.

About 20 years ago, after some unsuccessful trials with polyester and acrylic products, a new family of products was tested. Using materials with optimum adhesion (epoxy systems) on granite, the typical problems were resolved and a new technology was developed. The epoxy resin has shown the capability to run into each of the cracks and fill all of the pits and micro-fissures present in the granite. Additionally, its long hardening time allows the glue to penetrate deeply into the stone before the complete curing will occur.)

The slab then goes to a vendor: then goes to a fabricator:
You can seal with a water based sealer (that doesn't really do much) and/or a petroleum based granite sealer (much better) and there is a "color enhancer" petroleum based sealer.

When you have a "dark" granite: chances of you ever "seeing" a stain is slim!
But if you have a lighter granite: you will see a stain: ketcup: red wine: tomato paste: coffee: grape juice: OLIVE OIL: cooking oil: grease:
Why: #1 HIGH IN ACID/PH! #2: "could" penetrates through the factor sealer and the store bought water based or petroleum based sealer.

Do oil and water mix? Think of stains as a "science project"/chemical reaction!
That is why you don't seal "wet" granite with a petroleum based sealer: you are wasting time and your mony.

cooking oil of any kind with soak through (and or butter). High PH levels will soak through over time.

No:
No Lemon Juice
NO peanut butter!
No Orange Juice or citrus cleaners!
No ammonia
No bleach
No Oil
No coffee: very high in acid: not so good for stomach either! lol!
No apple juice
No red wine
No jellies

If you took a scrap piece of granite and soaked it in olive oil: what do you think will happen? It will permanently be "color enhanced" LOL!

High acid: will eat through sealers and brake them down.

Solutions:
Hard Rock Tools: great website: great company: they train their people well! I have learned a weath of info from them.
-Natural Touch Etch Remover 8oz
-Formula 51 Stripper Gallon(The Best Alkaline ********Cleaner/Stripper Available
* Removes Grease, Grime, Soap Scum, Hard Water Spots and Food Stains)
-wet POLTICE stain remover****** Non acidic stain remover: removes organic stains from surface of natural stone
-Deep Clean Gel
-Aqua Pro Water Based Sealer Gallon
-Ultimate Pro Sealer*petrolium based sealer
-Stone Pro Enhancer And Sealer**petrolium based sealer

www.hardrocktools.net (not advertising for them: I use their products always) I don't sell there products. I tell everyone about them: I believe in the product.
www.stoneproonline.com

Wet Poultice: safe Non-Acidic Stain Remover
is designed to remove organic stains from the surface of natural stone. some stains with permiate below the surface may require complete stone restoration to completely remove.
For best results: clean surface area with appropriate granite Safe cleaner first.
Requires:
-plactic wrap and masking tape. A wet poultice is desinged to follow behind the stain, agitate and clean the stain then remove and evaporate stain.
-cover stain area, using wet poultice compound / going one inch over the stain and covering the stain 1" thickness over the stain. Cover the stain with a plastic wrap. must be water proof wrap. then use masking tape completely cover and allow poultice to sit well for 24hours.
Poultice should absor into the stain. After 24 hours remove plastic wrap and let poultice set 24 more hours until dry over stain. This should "lift" the stain. Let sit until poultice completely dry and evaporate from the surface lifting the stain from the stone.
Aggressive stains may need another application.

***etched marks: need something else! Etch remover. If the stain has etched or dulled the polished surface: look for Stone Pro Natural Touch product to restore the luster and shine.

May have to call a stone doctor: although they may do this same process and charge you HIGH DOLLAR!

Might be a good idea to use "stripper" on the entire countertop. Let dry and remove stain, and then re-seal granite. If you are not able to sucessfully remove the stain.

On the hard rock tools website: there are stores all over USA and you can call them: they will answer questions!

Petra_Granite, are you saying that Maurizio Bertoli's formula should NOT be used? That's what the OP of that thread used with success.

Thank you for all of your suggestions. I showed it to DH and the stain had not penetrated--although I thought it had. So he just used his thumbnail and got it off. Thank goodness. Thank you!

This is off the subject, but grape juice stains are so permanent that is the secret ingredient of the paint used by Native Americans 500 years ago at National monuments.