Theodor Fahrner pendant in black enamel and sterling silver with mother of pearl and marcasites. This dramatic Art Deco piece dates from about 1920. The black enamel medallion is domed and teardrop shaped; it features a mother of pearl shell at the center. The frame is elaborate, open-worked, and studded with glistening marcasites. Large and commanding, it measures 2-7/8" by 1-3/8" including the bail and top ring. You can probably see that the marcasite bail is a later addition to the piece, a bit too small and lightweight, but functional.
The pendant is marked Sterling, Germany, but I know it is Fahrner, and I've included pictures of two examples of similar jewels. Fahnrer jewels were sometimes simply marked Sterling, Germany.
Looking at the reverse, you can see the green enameling is the same backing as the pin shown on the right in Photo Six. That brooch is pictured in Photo Seven, marked Fahrner. The pendant in Photo Eight is from my personal collection, not for sale, and dates from the same period.
For my listings I always refer to the Fahrner bible, "Theodor Fahner Jewelry...between avant garde and tradition".