There are many different ways to mark a grave for a loved one. It all depends on preference and if the cemetery has any regulations to follow. There are a couple different categories to choose from.
Uprights: They come as a unit as a Die and a Base. They can either be 6" or 8" thick.
Slants: They can either sit on the ground with or without a Base. They are 10" thick at the bottom and 2-1/2" thick at the top (think of a wedge)
Markers: They can be 4" and flush to the ground, or they can be Beveled, which is higher in the back and 2" shorter in the front. The Bevel Marker back measurements can be 6", 8", 10" or 12" and they sit on top of the ground.
Bronze: They are made from the precious medal Bronze and casted into the plaques.
Benches: Granite Benches can just be the seat or it can have a seat with a back. Can be for personal or cemetery use.
Pets: Can use a small slant, a marker or bevel marker, tablet, brick, heart shape granite, etc.