Just a word of warning(from personal experience) - its very easy to loose a stone from the 4 square stone setting.
I think the idea of this setting is to make small diamonds look like one impressive stone.
Check the setting thoroughly as unless each stone has some form of "claw" mount to hold it in, its very easy to lose one.
Sometimes if the metal holding the stone in is heavy it takes from the look of the style.
Not sure about the certification but at if its valued by the jeweller for insurance purposes maybe it doesn't matter too much.