And in my first comment I wasnt referring to defects on marbles, but the actual size. Modern machine made marbles, except for the shooters of course, all seem to be the same standard size. But I find solid colored marbles at old sites that are usually a bit smaller than the regular modern marbles still sold today at the 99cent store. Like clay marbles, they are found in different sizes, but always smaller than the regular ones we use today, and they are always solid in color. Clay marbles, as you know, were not all of one exact standard size but can vary in size. That said, I think the small solid ones I find are definitely older than than the swirly, colorful modern looking mables I find.