Can gel stain be used on ceramic tile around a fireplace?

Gel Stain is engineered for wood, but it has successfully adhered to more surfaces than we could have imagined. However, since tile cannot be abraded properly though sanding,  lasting adhesion may be difficult if not impossible. 

Milk Paint will have a better chance of adhering than Gel Stain. Dark Chocolate Milk Paint was created to match the color of Java Gel stain, for example. Both products are more likely to adhere if they are applied over a tile-appropriate primer. 

Contact a tile store for recommendations regarding a primer that can help finishes stick to ceramic tile. 

Even with primer, we cannot give any guarantees that the finish will adhere properly or last. Always test for compatibility between your primer and Milk Paint or Gel Stain before beginning.

If you choose to proceed, test your procedure on a hidden area first and let it cure for 7-10 days. Then further test the finish by duplicating normal wear and tear: washing, scrubbing, scratching, etc. to make sure the finish bonds to the surface.