I have one too albeit more blueish that I bought from a Dutch antique shop. The owner takes trips to foreign countries in search of antique tools and this stone came with 2 Grecian like LIs, a large LI and a slipstone LI. Might have been coincidence of course but if I had to guess I'd say LI It does differ significantly from the other types LI so it could easily be another type of stone.

I don't remember having seen one with a label, perhaps Neil or adrspach know more.