I think it is autthentic and quite sure about this as I know very well the owner, and it's not the kind of Guy to make some mistakes ...
But interesting, this is another thing, in regard of its price...
I think that for the price of this watch, you can get a DR SD, and a Triple 6 painted indexes, for example...I would certainly prefer these 2 to this Comex, but it's only my personnal take...
Best.
Nicolas