Bert said "I love marbles, so tremendous meeting those finds... the Group of 5 marbles on the right is known in English as 'cat's eyes'... they began to make in the 20's, but currently still make them, they are very difficult to date. The two blue you found on the beach, could be what is known as 'codd marbles'... came within a few bottles and used for sealing soft drinks (soda)... those bottles known as Codd... almost all marbles codd bottles were transparent, but also other colors venias. ... Is the blue that is alone in the photo a bolon (shooter)? The 'pontil mark' that you mentioned was the part linking the marble to the rod with which the made... when they cut it from the rod, was a little mark in the form of boost... certainly, that was in the marbles made by hand (19th century)... yours you say that it is somewhat oval, but still handmade marbles were almost perfectly round...
I hope that this help you"
Cheri, I agree with Punter.