There is no reason to believe your dial is not original. Do not use the serial number from the watch case. A" Your watch appears to be in good original condition and I think it is certainly collectable. The metal dial marked only Reliance tells us it was probably late in this period. Over twenty years nearly forty million dollar watches were sold, and Ingersoll coined the phrase "The watch that made the dollar famous! Inthe company introduced the "Reliance," a higher-grade jeweled watch. Here is what I have:
I just found this thread and can offer one good clue to dating Reliance watches if the dial is held to the movement with springy dial feet like the one pictured here.
Dating Ingersoll pocket watches?