Dating antique coke bottles
To the naked eye, these bottles will look pretty much the same.
The only differences from 1915 to present day for embossed bottles are changes in the trademark registration notice and patent notice on the bottles.
The very first Coke bottles were Hutchinson style bottles - these are extremely rare and date before 1900.
Straight-sided (S-S) Coke bottles with crown tops date about 1900-1919; colors were clear, aqua, green, blue, and amber with amber bottles in good condition typically bringing the highest prices.
One exception are those produced during 1942-45; these were blue due to the copper shortage for WWII (copper gives the green color).
There are also some amber colored hobble-skirt bottles.
Petretti's guide calls this era a "gold mine" for collectors.
The photo shows the various shades of amber that occur naturally, with the repro in the middle: a Macon GA S-S.
There are no natural amber S-S bottles from Macon GA.
However, these purple bottles do make a nice color addition to your collection.
There are some naturally occuring bottles with a light amethyst/purple tint - leaving them out in prolonged sunlight will darken the tint (but they will never become a dark purple).