Marble top repair should be done by a professional if you really value the piece. Most cracks can be bonded with a special epoxy then the chips along the crack filled with a resin filled with silica and pigments to match the stone. You could do it yourself, but if the piece is valuabe, its worth getting done right. A lot of marble and travertine tile is bonded and filled. I would guess the same process applies to restoration and repair. Check out a company that sells stone tile, countertops and that sort of thing in you area and get an estimate. If you deliver the piece to them, it would probably be very reasonable.