Let's call in some help. @Nantucketdink
Here's the album: http://marbleconnection.com/gallery/album/435-pward0212/
First thought ... the ones which seem like 1/2" are probably considered 5/8" to marble collectors. Just a small technicality. That 1/8" difference means a lot. But maybe you actually have 1/2"-ers ... which might be more collectable.
My next thought is that you could sell on ebay. Here's a list of recently sold Jabo Classics to let you know what you might expect there. (When you see "Jabo Classics", that usually refers to marbles from 1991 to 2007.)
https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&LH_Complete=1&LH_Sold=1&_nkw=jabo+classics&_sop=16