For the kerbstone /garden stone etc, we recommend a new design to you .which surface and around are natural granite, and the inside
is concrete
The advantage are as following
1) Cost will be less than the whole natural granite,
2) The surface could do the same finish with whole natural granite, such, polish, natural, flamed and mushroom etc.
3) the weight also will be lighter than all natural granite.
I think they will be good choice for you!