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. 
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