Two different processes put a design into granite. Families sometimes hear both called engraving. They are not the same, and a memorial can use either or both.
Sandblast engraving is the traditional way to cut letters and simple artwork. A stencil of the design is applied to the polished face. Abrasive under air pressure cuts the open parts of the stencil into the stone. The letters are recessed. They are then usually filled with a lithochrome paint so the name reads from a distance. Sandblast is the right process for names, dates, borders, and emblems that should stay deep and legible for a long time. The edges are crisp. The letter is a shape cut into the granite, not a picture of a letter.
Laser etching uses a fine beam to mark the polished surface. It can render a photograph, a landscape, or a detailed scene in shades of gray. It does not cut a deep letter the way a sandblast does. Contrast is highest on a dark, polished granite. On a light gray stone a laser portrait can look faint, which is why dark granite is the usual choice when a portrait matters. The image sits in the polish. It should be treated as artwork, not as a substitute for the name.
Most monuments use sandblast for the name and the dates, because those words have to be read by someone standing at the grave. A laser portrait, a scene, or a faithful copy of a signature can sit beside that lettering. Using both is normal. Using only sandblast is normal when the family wants words and an emblem and does not want a picture. Using only laser for the name is a poor trade. The name should be cut, not merely marked.
Bring the artwork in a form that matches the process. A laser portrait needs a clear photograph of the person, chosen the way you would choose any portrait for a small oval or panel. A sandblast emblem needs a clean shape: a cross, a service mark, a flower, a simple scene. Fine hairlines and tiny text disappear in a sandblast. They may survive in a laser panel if the granite is dark and polished.
Ask to see the inscription on the stone, or on a proof of the portrait, before anything is cut. The words and the picture are the part of the monument your family will read. The process is only how they get there.