Solid 14K Gold Faceted Black Onyx Brooch

Vintage 14K gold faceted Onyx bar Brooch. Solid 14K yellow gold. Mark has wore over time or I haven’t found it. But has been tested with acid and verified AT LEAST 14K 585 gold. Weighs 12 grams. 2 1/4” long and 3/4” wide. EUC! Have matching necklace if interested plz message me! Thanks for looking!