Many options for personalized grave markers have become available in the past ten to twenty years. One of those options is having a portrait of your loved one emblazoned on a ceramic oval and then affixed to the marker. These can be very nice, but they do have their issues.
For one thing, if water gets behind the ceramic memorial piece, it can freeze and pop the portrait right off the stone. We have seen these memorials lying rather forlornly in the grass near the marker they were previously affixed to. Also, if not done correctly, the image will fade in only a few years and you will be left with just a blank white oval.
To help compensate for this, some companies inset the memorial photo into the granite of the stone, thus helping avoid the problem with freezing. And to help avoid both freezing and fading issues, the company can inset the ceramic piece into a metal frame that comes complete with a lid, and then can secure this frame to the stone with screws. To view the portrait the visitor must move the lid aside.
Putting a portrait on a stone can be a relatively inexpensive way to personalize something that is often very generic and bland, and can be a nice addition to a headstone. Just keep in mind their limitations!