Terry,
Indeed these ‘subdued’ rank and qualification badges are generally ‘unofficial’ and not issued. Large selection in my album
https://www.britishbadgeforum.com/fo...hp?albumid=866 includes a number of medical badges.
They do come in various shades of olive green and desert colours but as Paul says photography and lighting can affect the colour you see.
However, I believe many are/were worn by service personnel on uniform or equipment. Usually attached by hook and loop (Velcro) so they can be removed easily.
Tim