Dolly Boucoyannis 20 Drachmai necklace. It comes with the box and note, as pictured. It's never been worn.
This is the Google translation of the Greek on the note:
The reuse of a genuine old coin, of silver 20 of 1960, crafted by the sculptor and engraver V. Falireas, symbolizes the least possible everyone can offer for the rescue of our planet.
Just the thought that some object can and should be reused makes us shareholders in this global effort.