This key is one of several I brought back from my fall trip to Rennes to the second largest flea market in France. It is about 2-3/4 inches long with a hollow barrel shaft and the ornate handle is about 1-1/8 inches across. It weighs 21 grams. I readily admit that I'm not a key expert, but as I hunted for treasures, I looked for the keys that showed age, patina and all those other wonderful signs of authenticity as well as signs of artistic workmanship. This key seems to have all of that! According to my online research, this key is likely from the 19th century, used for a cabinet lock or some other kind of furniture.
I've included several photos to help show off the multiple layers of glitz and glam.