The stone had to be an Ashlar stone.
You may ask, what is an Ashlar stone?! An Ashlar stone is a stone that has to be cut finely, often cubed and with a fine cut finish. As stone doesn’t come in this finish, our Stonemason had to utilise all his skills. The stone was fresh cut stone so he had to use his secret treatment to ages the stones colour and then cut in a fine herringbone finish.