Based on the age wear and the resemblance of the signature to the paper label, it appears it may be an original piece. I can not state that 100% though, as I can not find info regarding the markings and whether the crystal pieces had embossed trademarks or not, and if so, when they started. I can not find any images of them either....
If an original, IMHO it would place the date of production, most likely between 1934-1945, as the firm was pretty much gone by the end of 1945, although the molds still existed, and I am unclear as to the amount of use they were receiving at the time. The "crystal" Ingrid figures appear to have been introduced in 1934, but I can not find any info telling me when this particular piece was designed or produced in the period of 1934-1945. I also can not find an image of an original to compare the detail in the mold quality.
The information I have is that after 1945 the molds were the poroperty of the Josef Riedel Glassworks, the company that had actually manufactured the products for Schlevogt and Hoffman, and after 1948, were considered the property of the Nationalized Czech glass industry. I can not find any info on production of the Ingrid pieces during these periods.
Jindrich may be able to shed more, and possibly more accurate information on the subject. I am limited to researching sources in English, and I am sure there is a much greater abundance of material in Czech... a language I unfortunately do not read or speak.
I hope that this is helpful, and if I can find any additional info regarding the piece I will post it here.