I inherited a glass bowl, which in my grandmother's inventory was described as a "Swedish Green Glass Bowl". It is emerald green, about six inches tall and six inches wide, smooth, globular, thick, with a hexagonal opening on the top. The edges of the hexagonal opening (three and a half inches from point to point) are convex into the opening. The smooth glass is slightly "paneled" in that the sides of the bowl are slightly thicker under the sides of the hexagonal opening, and slightly thinner under the points of the opening, giving a beautiful variation in the green color It has a hand-engraved signature on the bottom, from left to right: the letters O F, then the letters L U (with a tail) and the model number 1531. My grandmother would have probably bought it in the US in the 1930's or 40's. I have attached two pictures, one of the overall bowl, and one of the signature.
Could someone help me identify this piece, and the significance of the markings. Is it a standard piece from a manufacturer's catalogue? Thanks for your help.