looks like iron oxidation. I would first check to make sure there isnt any moisture and than I would poultice with iron out.  It might not come out if its been there too long..but its worth a try

On Thu, Feb 7, 2019 at 4:50 PM john kunz <johnkunz@tnstonecare.com> wrote:
I think I know my answer but hope someone has a idea. Client is really bothered from this yellowing coming from grout lines and stone. Any remedies to remove yellowing. 
Second pic is not correct stone color just bad pic ... it is Carrera marble 
Thanks 
image1.jpeg
image2.jpeg
John Kunz- owner 
615-351-4676


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