The brooch part is marked Coro Duette in script with a patent number on the bottom. The clips just have the clip patent number. The whole piece measures about 7/8" high by about 2 3/8" wide.
This is a fairly small piece. The hardware works properly, but please note that I've found the clips will only go in properly one way--if you switch the clips in the brooch, one clip doesn't close flat. You just have to switch them around if that happens.
The item "Vintage CORO DUETTE Rhinestone BROOCH Dress Clips Art Deco 1930s Pin Convertible" is in sale since Monday, August 31, 2020. This item is in the category "Jewelry & Watches\Vintage & Antique Jewelry\Costume\Designer, Signed\Pins, Brooches". The seller is "cleacarlsen" and is located in Santa Fe, New Mexico.This item can be shipped to United States.