Antique best Enamel Lady Slipper Pendant

I love old enamel pieces. Typically enameled on silver, then coated with a low carat gold, or rolled gold.
This little lady slipper does not disappoint. The drop from chain to tip of the flower is about an inch and a half.
This is marked "silver" on best the back of the flower.
It measures an inch at its widest. Just to date this a little bit, the marking "silver" instead of
"sterling" or "925" would be between 1906 and 1981. I believe this is circa 1920.
The chain is gold-tone, and measures 18 inches.