Thanks Jim, It would also be interesting to find out when they started to pit "serial numbers" on dice. These for sure are from the early days. But also some are deteriorating because they used a different chemical composition back then, unfortunately.
I told my son he might want to sell the whole lot to a dice collector or dealer instead of listing them by the pair on eBay. Of course, I also told him by listing them on eBay he will get the most out of his purchase.