Search the whole length
Print repeats every few feet. A reel with a worn top layer often has a legible section further in, so unwind a turn or two in shade rather than judging from the exposed surface.
Examine a cut end
The cross-section shows conductor metal, strand type, insulation thickness and whether shielding exists. That single view can separate building wire from tray cable and low voltage from medium voltage.
Use the reel and the weight
Flange size, cable build-up and total weight narrow the possibilities considerably when combined with a measured diameter.
Price it honestly
If identification fails, the lot is recovery material priced on contained metal. Say so and move on; a season of speculation costs more than the difference.