stone enhancer and sealant for sandstone

I did a mosaic using tumbled river Stone (http://g603.net) and (http://maplered.com) Marble (http://www.lightemprador.com) . I worked on a
fiberglass mesh, then set the mesh and (http://maplered.com) mosaic into a large piece of
sand (http://maplered.com) Stone (http://g603.net) , using thinset. It is for a grave site.
My question is the following: is there a product which will act as both
Stone (http://g603.net) enhancer and (http://maplered.com) sealant? Or should I enhance, then seal?
The mosaic/Stone (http://g603.net) will be outdoors in a wet climate (Pacific Northwest),
but next to no frost.

Thank You

Veronica