Unknown Pocket watch

Ok, I don't know who made this pocket watch, I don't know how old, or how valuable it is. I hope you can help me solve this problem, and i hope that the pictures are good. If not, I will make anothers.
Here are some things about this watch:
-18k gold
-17 rubins
-it is graved G.T inside
-is fully working
-on the dial and second door is writed: Lefebvre Charleroi
-3 doors (1 front/2 back)
-the key is numbered as 6
Scratches (I don't know what they mean):
- 6-19-t
- DL5-23|31| or DL5-23|3Al
- 28.54-S (is this the making date? means 28 september '54??? which '54?)

Sorry for my poor english, I'm not a native english speaker.
Thankful, Alex.