(Specifics on what a pontil looks like or how to tell the age based on the mold seam can be found in Bottle Basics.) While these two characteristics are often a strong clue to age, readers will be further helped by developing an understanding how the various categories of bottles changed over time.
In the center of the Owens Ring the Owens mark is shown the diamond.
Slowly the corked top bottle began to disappear in favor of the screw top.
Perfumes and whisky and other alcoholic beverage bottles of this period often retained their cork closures.
the right side is crude and was disturbed by the action of marking the marking with Owens Ring.
Owens rapidly made improvements as eh redesigned his machine numerous times and eventually over came the problems of uniformity see here.