Thanks for posting.
I suspect that the source of your information is the same as mine - page 128 in Antique Glass Bottles by Willy Van den Bossche. The author provides information on eight seal bottles related to Constantia Wine, produced at a S. Africa vineyard named for the wife of Dutch Governor Simon Van der Stel. He describes the long neck form, in general, as a "langhal" which dates from the era 1760 to 1840.
The wear on your bottle does affect its value - I would have to give a wide range since I am not entirely certain of what it might sell for.