Edith,
Your inherited vintage pearls look like imitation pearls to me also. In their day, they were often quite expensive and treasured just as our cultured pearls are today. They appear to be in very good condition.
You may want to restring them yourself. Pearl Dreams has an easy to follow tutorial for knotting under the Lowly Beaders Club. The multistrand isn't knotted and could be easily restring with designer wire and crimp beads.
They don't have a high resale value, but as a remembrance of someone special they are priceless.
Many of us here wear and enjoy imitation pearls as well as "real" ones!