Try a slim porcelain sheet in a concrete look finish. The large format size means you'll probably need only one, so there'll be no grout lines. Have a look here, at the Portland 3.0. I think the Kerlite range also does a concrete look and is larger, at 3m long. The other advantage of a porcelain tile over actual concrete, is that you just wipe it down. Concrete is porous and will stain.

The tiles from Johnson in the UK are stunning. It appears they only come in large 30x30 ? I was thinking of doing some sort of tile art just in the middle of the backsplash with the rest just plain offwhite tile. However, with this large 30x30 art work, the background tile would have to be cut to size to fit the area I have and might look too choppy???

Your kitchen is small and already quite busy. I would make it as simple and clean as possible. You can't beat ceramic tiles for cost, durability and ease of installation. Have a look at Johnson's Spectrum range to see if you can match the green. https://www.johnsontiles.com.au/product/spectrum/?utm_campaign=1602072422&utm_source=google&utm_medium=cpc&utm_content=304640004469&utm_term=&adgroupid=61761480198&gclid=CjwKCAjw_YPnBRBREiwAIP6TJ0idAicM8vfEevC-WrwRVNmbtUPHfDAjvNpkaOIo0hzN0dwMw9u1rxoC0VkQAvD_BwE You will get a neater finish with ceramic tiles than you will with trying to work with DIY stainless steel, particularly around the edges. There are lots of online resources to show how easy it is to lay smaller ceramic tiles. Leave the large format porcelain tiles to the professionals. Best of luck, Dr Retro of Dr Retro House Calls

Hi Mimi, Your stone (probably Marble or Reconstituted stone as these can be damaged by acids) has been factory finished by diamond polishing to get the gloss level it has. A sealer will only help protect that factory finish and unfortunately it will not bring it back. The bad news is it is not possible to repair and so removal and replacement is the only real fix. This may be covered if you have Accidental House Insurance, but other than this, I am afraid there is no easy fix, sorry. Hope this helps though, Malcolm.