Having had another look at the vase in the Catawiki link, I'm not sure about its signature, even though I believe a piece should never be judged on just that. I have once come across an engraved signature before, written as in the cameo style from +/- 1905 but can't remember the piece.
I have never seen a signature 'V st L', nor do I have any examples of it. Besides that, at VSL a diamond point signature wasn't used until the 40ies and this piece is earlier than that.