Vintage Ladies Cocktail - odd numbers. Logo not in 12 position.

[pparents]

I recently inherited this lovely watch from my grandmother. It's engraved, and most likely was given to her by her husband, so between 1928 and 1953. It says Rolex, but the logo is different from all the pictures I see on the forums, and I can't find a guide of women's cocktail watches. Is this a real rolex? What decade most likely? How does it open? No visible means of access from the back.