Fix broken marble by gluing the pieces back together with either an adhesive created specifically for marble or a two-part epoxy. As long as there are no large pieces missing, the marble can be repaired and put back to its original use.
Clean the marble thoroughly before making repairs, as the adhesive or epoxy works best on a clean edge, A nylon brush drawn along the broken edges removes any loose marble particles that can interfere with the perfect alignment of the broken pieces. Acetone is also useful when cleaning the edges as it creates a surface that accepts the binder better.
Once the edges are cleaned, cover the two edges of the break with the adhesive or epoxy and press them together. Wipe up any epoxy or adhesive that seeps out of the mending area onto the surface of the marble using a damp rag. If the piece is a slab of stone, use clamps to hold the edges together and allow the adhesive or epoxy to cure. If there are small chips missing, fill the holes with the epoxy or adhesive to create a smooth-finished surface. To provide a color match to the original piece before filling in any holes, mix the adhesive or epoxy with equal parts marble dust that are the same color as the original stone. After curing, remove any excess adhesive or epoxy left on the marble surface with a razor blade scraped along the broken line.