Kezhart, these are ceramic mosaics from here-
If budget allows, you can get nicer ones in marble here - https://designermarble.com.au/collections/nero-marquina
(the 50mm size)
Alternatively, we also have the goods if you are unable to find what you need from those other sources.
Hope that helps!
Kitchen splash back
Fixed shower screens, does too much water spash out or not?
Where to get purple floor tiles
Need help with where to go from here