Lesson Learned:

We have had a total of 13 dogs over the years and when one passes away I make a headstone for them and put them where we see them every day to remember them. I noticed the color photos on each had faded out to where we couldn't see them very well and the epoxy that covered the stones had darkened. 

I am currently re doing the headstones with black and white photos that should not fade or get dark and a new epoxy that should not yellow or turn dark. The photo below shows the new headstones. Two down, 8 more to go. It may take some time as it is a 4 step process. 

Step 1: wire brush and clean the stone. 

Step 2: stencil names on stone.

Step 3: Glue photo on stone.

Step 4: Mix epoxy and apply to top of stone.

Lesson learned - don't apply epoxy thick and use just one coat that will cover and seal the top and to use black and white photo's and not color photos that will fade in a few years.