...this type of women's dress watch is commonly call a "cocktail" watch. This is probably because it is so small, dressy and impractical, it was worn mostly for dress-up occasions.
Today, women prefer larger watches, so these don't have much collector value above the gold and/or diamonds in the case. This is a shame, as they are marvels of engineering for their time. When new they sold for more than equivalent men's watches.
Wish I had better news, and please wish your mother a Happy Mother's Day,
gatorcpa