Watch maker with initials S.A.D.

[karensue]

I have a gold(?) watch with the maker's mark of S.A.D. inside a shield. The mark is on the inside front cover and on the movement. The shield on the cover also has a crown above it. There is also an eighteen with a crown over it on the cover.

Does anyone know who S.A.D. might be?

I would appreciate any information you can give me.

https://secure.filesanywhere.com/MediaL ... %AAu%AE%A3

https://secure.filesanywhere.com/MediaL ... D%A1v%B3on


Thank you.
.