Definitely a Jobling Flower Pattern bowl with a likely spurious mark. From the strong, more whitish opalescence and apparent lack of a registration number, I'd think it was quite an early example (1932-3) of Jobling production. The mark was most probably added later to deceive. However, there is some history between the companies, as Jobling apparently did approach Sabino with the intention of producing Sabino designs under license in the UK, though apparently no agreement was made as Sabino wanted too much money. Jobling did copy Sabino's Les Hirondelles pattern though for their 2606 pintray...
As Sue has said, this broad engraved Sabino signature is more common on newer pieces. On the pieces I have which I can positively date as pre-war (shapes which haven't been re-issued, earlier colours/ finishes), the marks have either been moulded, diamond point incised, or engraved with a finer-tipped tool.
As for engraved marks on Jobling -- some opalescent pieces were marked "Jobling's" "Opalique" in engraved script from late 1933 onwards (the earliest piece thus marked that I have seen is a large lambton bird bowl). Some pieces also have engraved "Regn. Appld. For" marks, showing they were made before the design registration number was added to the mould.
The modern Sabino Crystal Company have reissued some old designs which were originally not sold under the Sabino name. From their current online catalogue, I recognise an Etling figure and vase, as well as two bowl designs which were previously sold under the 'Ezan' name. There are also other vases in the catalogue which are not shown in Decelle too and are either later designs or moulds acquired from elsewhere. I am not aware of Sabino ever having produced Jobling patterns, and it's generally believed that the Jobling moulds went to other UK makers -- certainly we have evidence of the small Bird & Panel vase mould ending up at Sowerby, while Davidson also reissued Jobling's jazzy cigarette holder base/ ashtray in the sixties.