Those type counter tops are quite porous-
How busy is the kitchen?
How porous are the tops today?
This stone requires repetitive or multiple applications of sealer-
Try cleaning the darkened areas with a high alkaline cleaner-let it dwell for a while to break down the grease or oil- 
Then you can do the sealing thing-better test a piece of that in the shop before sealing-so you have an idea how to seal-

On Mon, Aug 22, 2016 at 11:42 AM, Mike Alston <realmikealston@gmail.com> wrote:
Good morning, customers had this granite countertop installed June 2015. The installer has since cleaned and sealed with Tenax pro-sealer.  The customer insist that then have not used any cleaner except soap and water. The photo on top is a piece that has been sitting outside since the install. Only the used countertops are darkening. image1.JPG

Sent from my iPhone

On Aug 19, 2016, at 9:17 AM, stuart rosen <mail@stoneshine.com> wrote:

Hey Michael,
We will need more info-I doubt the entire surface has darkened-when you make your visit test porosity of the stone.
It may just be oil stained-in some areas.
Some folks will buy and apply all kinds of "stuff "(look under the counter) to protect and keep their stone looking its best.
You will find a build up of that  "stuff " may be causing the issue.

On Thu, Aug 18, 2016 at 10:03 PM, Michael Alston <realmikealston@gmail.com> wrote:
Good evening fellow pros, I apologize for posting so late but a fabricator has a customer whom they installed a silver and black granite counter top last year. The customer has complained that it has darkened and has become more black than the blended color she purchased a year ago and want to know why and if it can be repaired. She had not been forthcoming on whether anything has been used to clean the counter top.I have only seen pictures but plan on taking my own this weekend. Any suggestions before I make a visit to this woman's house, thanks. 

--
Michael Alston
President
Surface Care Pros
Phone: 336-497-4283

SurfaceCare Pros


 
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