Question: I am trying to determine what these blue photos in my family collection are? They look like they are pictures of my great-grandparents around the time they were married in 1902.
Answer: The photograph you have decide is a process known as a Cyanotype. The process creates a cyan-blue image. The time frame I see these in vogue ranges 1890's to the 1910's. So your date of 1902 fits in quite nicely. The process was the first way of adding a non-sepia color to an image, without hand coloring.