Judging by Edoardo's wording - "I need you to help me to know if this piece is true or false", then something a little more definitive than an opinion was required, which prompted me to reply.
The problem with responding to requests such as this is that folk get carried away and it's all too easy to say the wrong thing - however, let's hope someone is able to help Edoardo

P.S. During the C20, the style of the signature of this company varied ........ sometimes u/c sometimes l/c, and it would appear from the books that designer codes and supplemental codes for categories of wares were used, often. The date of c. 1930, included with this description, does make the implied date a little earlier than coverage of Orrefors in most of the books on modern glass. In the absence of such information this one is perhaps not so easy to comment on ............... but that's just my opinion you understand.

PPS - As has been suggested in similar situations in the past, Edoardo might consider contacting the seller to ask for details to support the provenance/attribution of this item - certainly no harm.