Design wise I think the site is great. Its clean, simple navigation, easy to read and all the relevant information is there and easily found, to give you a good solid web presence.
Again, in terms of
SEO you need much more content, perhaps a page about the history of stonemasonry, try to be inventive with the content.
I realise you're a relatively new company, so testimonials may not be available yet, but certainly some photographic examples of your work would be a real benefit to the website, and as a potential client I would want to see that and it could really sell me your service.
Try looking at competitors, or similar types of sites who come high in the SEs for masonry, or simiilar lines of business, and see what content they have. I wouldn't suggest stealing it but it could certainly help inspire you!
good luck, great design well done!