Topic: unknown numbering system on glass vase poss Scandinavian

[bobsywoman]

Hello I have a very nice quality very heavy torpedo or bullet vase about 22 cm tall with a beautifully poliched rim and lovely markings. It looks really Scandinavian and is very clearly initialled and numbered on the base '530A  4' (there is a big gap between the letter A and the 4) . Try as I may I just have not been able to ID the maker -I thought Orrefors or Kosta Boda? but I am not sure the initials/numbers fit for those makers? If anyone has any clue or even suggestions I could follow up further then I would love to hear from you.
Thank you and crossing my fingers!