Identification of a S.T. Dupont Lighter

It's a lighter of my grandfather's, which was recently found when cleaning the house. I'm unsure of what make and model (Ligne, or whatnot) the lighter is, and was wondering if you guys could help me out!






The back of it reads:
"S.T.Dupont
PARIS
MADE IN FRANCE
[Gas Canister Screw]
20µ
[Seal]
FA6923"

The story is that my grandfather was given it by an Arabic Sheikh in the early 1970s. That's about all I know of it.

I was curious if anyone could enlighten me on the specifications of the item, and an idea of the price range it could be sold in. I haven't been able to find any concrete information on it, as I haven't found an image that matches it exactly.

Thanks all!
-Twidge