Information about this knife was found in the book Victorian Glass Novelties (Schiffer Book for Collectors) pg. 134. OPAL KNIVES, DECORATED AND SOUVENIR. No maker is listed.
It is too thick to open a letters. Thank you, Pamela, for your reply.
Pamela.
I would like mention to you about Niemen (Neman) glass work info on your site. This is not a Polish company, used to be Russian, now is Belarusian.