Carnival Glass

So I have become a fan of Carnival glass to resell. I have now quite a few pieces I have won at auctions and sell on several sites and local sales. I do strive for my listings to be accurate. One thing I am having trouble with is finding if my glass is a recent reissue. I posted a tumbler that was id'ed last night as Imperial #473 Grape in Marigold. The person who id'ed it said c1914. I look on Ebay and there is a seller who has the same tumblers and says its from the 1960's and is a reissue. How do I know if it is a reissue. I have read several websites from google searches that stated what I understand as the reissue of Northwood, Imperial, and Millersburg have stamped trademark, where-as the originals do not have any markings. Is this an accurate way to tell? Any help appreciated.

 

Look down inside your glass. Imperial glass from the 1960s had a mark. I superimposed over G.

Have you discovered David Doty's carnival glass site?

 

I looked a little on that site for ID of the glass. I will search the site deeper to understand better it seems.

 

it's often not possible to know exactly when a piece was made. The 1914 date provided was the initial production year (YOP). Imperial, as with other glass makers, would often reissue their patterns for many years up to the time of their closing. Many of their later items were marked with various maker's marks or logos. As cluttered mentions the mark may be inside the bottom of the glass or on the bottom. Without the mark or specific production data it is difficult to know a specific date. Often the date isn't that important and many sellers have no clue. Ddoty can be useful in their tracking of eBay sales to give an idea of values in some cases.