We have a customer with a lot of Impala Black on their landscape boxes and pillars.  The bottom of the stone has a bit of spalling and has turned to a a light color.  They are hoping to have this refinished. 

It is about 10 years old and has never had any maintenance done.  I believe that the light color may be effloresence, but is right next to a walk and driveway that is salted in the winter.

I’m looking for suggestions to save the customer having to replace the stone.  They are not expecting it to look perfect, but would like the color back.

See attached picture

Thank you