This is a handsome piece. Likely a bespoke piece, that was commissioned by the family who’s crest this was. French. Modelled in 18ct. The  French eagle is found twice, once on the pin and once on the c clasp. There is also another stamp which I cannot read. Fabulous gold work, with real strong detail. The lapidary work of the lapis is also very good. Can you see how the gold slots through the lapis shield?? Set with three bands of rose cut diamonds, and featuring three plump natural pearls. There is a hook which can be used to hang something from, or as a pendant loop. The most intriguing part - the letters ‘P D’ are carved to the back of the lapis. Were these the initials of the family? 
14.3 grams