It is a great question, thanks for posting.
Antique bottle value is based on a number of criteria such as rarity, condition, age, relative quality of the individual piece, etc. There is also an established track record for sales and even published auction records. So value can be somewhat mechanical in that you can review the sales history and get a idea in a simple way. However, there is an element of connoisseurship that takes value to another level of refinement - one judges each piece against others of its kind (or mold) and answers such questions as:
is this the best example of its kind?is this a rare color for this mold or a common one? how hard is this bottle to obtain?how is the clarity of the glass and the crispness of the mold impression?and so on.
The quest for perfection and quality is never ending with the collector...it makes collecting both exciting, and for those who are self-aware a bit frightening because things can get a bit obsessive. I know a few collectors (and there are probably more I do not know) that have invested every nickel they have ever saved into bottles....
Chris
