This is an extraordinary pair of matching Art Deco jabot pin brooches. It is set in platinum with round cut diamonds, cabochon onix and black enamel. They will be auctioned by Christie's in Geneva on November 13th. The brooches are unsigned, however the estimate is quite astronomical for the value of the gemstones, it must surely be due to the rarity of the design.
A "jabot", is a kind of ruffle worn on the bosom of a man's shirt or woman's blouse. The "jabot pin" was designed to hold the jabot onto the shirt. It is basically a pin with a brooch at either end.