Very Rare Avon Cape Cod Collection Cobalt Blue Wine Glasses

I have two cobalt blue wine glasses by Avon the 1876 cape cod collection. One is stamped on the bottom Avon 4 and the other one is stamped Avon. I have researched these before and I have not found much information on them. I think they were made by error or possibly made for color testing purposes. I would like to get more information on them and I would to know thier value. Any information would be appreciated. Thank you