Any chance that the guy who sold you the brass rod had a name or number or specification for it?
Like, common designation C260 is cartrige brass, 70% copper 30% nickel. About the same as the sheet brass you use for inlays, patchboxes, thimbles.
Brass rod, huh? It wouldn't by any chance be brazing rod, now would it? If so, that would be a different chemistry, so a slightly different color, than the 70Copper 30Zinc you are using for brass inlays.
Maybe buy your rod somewhere where you can indeed get C260 (UNS C26o00 brass)