Open Filigree Pin 2.5ct Opal 0.36ct Diamond in 14k Yellow Gold 13.2g 1.5", circa 1930-1940's. Open work in floral design, it embellished with eight (8) oval cut natural Opal, 6.95 x 5.58mm, with center round Opal (4.0 mm), and surround by six (6) round brilliant Diamond, approx. 2.5mm. Total weight of opal approx. 3.78ct Opal and 0.36ct diamond. 
The brooch is 1.5" x 1.48", weight 13.2 g (solid gold), C-lock pin, hallmark 14K