I will admit to having a passion for collecting the Fenton Eggs that borders on an addiction.
I currently have 68 unique eggs in my collection and multiple duplicates.  Since these eggs are all hand painted, I find myself purchasing multiples of the same egg just to see the slight differences in the artwork, and how each artist various just slightly.  I kept telling myself that I would find the one I liked best and put the others up for sale.  That is what I kept telling myself, not what I was actually doing. 

Since I also collect Carnival glass, Fenton animal figurines, open salt cellars and toothpick holders with the same philosophy, the inevitable happened, I ran out of display space.  No matter how I rearranged things, I was not fitting another piece.  So it was time to part with my treasures.

I sat down with all the eggs that I had multiples of and looked each one over.  The ones that appealed to me most, were returned to the display, the others moved to a shelf in the home office to be put up for sale. 

What made me choose one egg over the other?  I'm not sure, they are all beautiful, in some cases it was the first one that I had purchased that stayed, in others I found I preferred one artist over the other and when I was struggling to make up my mind I closed my eyes and picked.  In one case I have kept the egg with a slight chip, since turned the right way on display only I know the chip is there. 

I love to research, and before I put an egg up for sale or auction I research it so that I can provide as much information about it as possible.  I have several up for sale in my store now and more coming as soon as I finish the research on them. 

Will I ever run out of eggs to sell?  Probably not for I find myself still biding and purchasing eggs even though I already have one just like.

The other day I received an email asking me how I knew an item I have up for auction is the Panther Pattern by Fenton.  Researching vintage glass, especially carnival glass is a passion of mine, so I have quite the resource library.  If I do not readily know what the pattern is I will research it before putting it up for auction.

The 3 books that I would recommend to anyone starting out are:
Standard Encyclopedia of Carnival Glass, I have the 10th edition, and the 11th is on its way to me.
Warman’s Carnival Glass, I have the 2nd edition
Warman’s  Compnion Carnival Glass
These books have a wealth of information and between them probably every North American pattern known.

So as to the question, how did I know, well in this case I knew the pattern.  But I provided the following reference information:
An excerpt from the Standard Encyclopedia of Carnival Glass: Panther: This interior pattern from the Fenton Art Glass Company is found in large and small berry bowls as well as a centerpiece.....

An excerpt from Warman’s Companion Carnival Glass
Made Fenton
Colors known: amberina, amethyst, aqua, blue,..
Forms berry sets
Identifying characteristics: This interior pattern features two large stalking panthers accented by scrolling foliage.  The exterior pattern used is Butterfly and Berry.  Production began in 1914. 

And last but not least a website where the person could view the pattern themselves

 http://www.ddoty.com/panther.html