Pioneer is Federal Glass Company's name given in appreciation of patterns of old cut glass pieces in an earlier time.  The fruit pattern is what I am writing about in particular.  The pattern is being copied (Made In China) and being sold in Dollar stores.  I am not sure if I can say the name here but I quite sure you know the place that I am refering too.  This is to warn both sellers and buyers alike since I have seen pieces on ebay from the D store.  There are people removing the bar-code tags and selling them to both the wary seller and the unsuspecting buyer.  Telling the difference is almost impossible except in the feel.  The federal ones are heavier than the fake ones. 

Petal pattern also by Federal Glass Company is also being faked as well and sold in the same place.  It is harder to spot except in the weight it's a bit lighter.

My advise would be to know your seller and ask questions and keep an out when shopping in the motar and brick D place.