Valuable, early pieces of Coca-Cola memorabilia are often reproduced or faked. Fortunately knowledge of Coke's changing designs can often help to date and authenticate pieces, as many fakes are not accurate. Further confusion arises as some companies who produced Coke advertising in the early 20th century used outdated logos. Pieces by such companies may seem to be earlier than they are but they are not actually fakes.Compare your piece to authenticated originals in reference books and look for differences in the detail. If you can't find an authenticated example of your piece in a reference book, you may have what is known as a 'fantasy'. Such pieces were never released by Coke and have been subsequently invented by forgers.
Forgers sometimes produce Coca-Cola items such as gumball machines, cash registers, penny scale or cast iron banks and toys. But, one should know that these items are pure fake for the simple reason - Coca-Cola company never produced any of those items. So it is impossible to find them as the authenticated items.
Even high-quality colour copy machines easily can copy old Coca-Cola images and reproduce them. Such items you can find on eBay, and the best way to be suspicious about them is to check their size. Many of them are in A3 format that matches standard paper size for today's copiers. A bit of tea - and you have an old, stained Coca-Cola ad! Porcelain Coca-Cola signs (oval, round or rectangular) are mostly produced in India and other countries. They don't have trademarks or manufacture info, and all have aged look with chipped edges.
We can recommend "Petretti's Coca-Cola Collectibles Price Guide: The Encyclopedia of Coca-Cola Collectibles" by Allan Petretti as an excellent source of information and guide.