Have you burned a fire? The stone above the fire box looks like it's drying out.

Did the installer follow the installation instructions? I looked up a similar product and this is what was mentioned.

• We recommend using white good quality thin set such as Mapei, Laticrete, or Ardex.

Thanks for your reply.
We have not burned a fire.
He used Māpei thin set in white.

I would burn a fire and see if the tile above improves in color.

Thank you!! Your suggestion made me think I could manually dry the tiles. I have 3 fans running and it seems to be drying. Thank you for the suggestion!! I’ll post a photo once it’s seemingly dry.

We ran the fireplace last night. Unfortunately, no change.

Are the installed tiles and the sample from the same batch? Or the sample is the one you took from showroom before?

These are from the same batch.

If you have a heat gun give that a try.