I had a contractor come in and lay new tile in my home. When the job was done, there were 2 or 3 tiles that were uneven and we asked the tile setter to chip out those tiles and replace them.
For those 2 or 3 tiles, I suspect (for various reasons) that the tile setter used mortar (Versabond thinset) between the replaced tile and its neighbors rather than grout.
How can I tell for sure?