18th C. French Spoon with foreign CD mark?

[Francais]

This is an 18th C. French spoon. The French marks I know, from memory Paris 1777 Pierre Nicolas SOMME. The last mark is the crab .800 mark obviously added later, but what is the CD mark. My guess is: it is a foreign maker's mark, back stamped. It can't be American as it is too small. Does anyone recognize it?