Authenticating 1909-S V.D.B. Lincoln Cents can be problematic for inexperienced collectors, but learning just a few die diagnostics will give you an upper hand when examining this valuable key date.
First, you need to make sure the S mint mark is the correct shape. It should looked “boxy” and there’s four obverse orientations. View them here.
The V.D.B. on the reverse should be a little left of center, and finally, there should be what some call a “pimple” inside the top loop of the S mint mark.
If the coin has these three diagnostics then it should be authentic and a safe buy. You just don’t want to go in blindly, taking any seller’s word, when purchasing such a rare and valuable key date raw.
There’s been instances of the S being added to a 1909 V.D.B., as well as the V.D.B. added to a 1909-S, and the coin used in these alterations might be authentic, but they’re obviously not an authentic 1909-S VDB examples, since being altered.
Also, there’s other diagnostics that can be looked for, but can be more difficult to ascertain on some examples. The N on the reverse should appear “shallow”. The second period, after the D in V.D.B. will be centered, some fakes will have a period that’s too far left. The V.D.B. is distinct and never looks “mushy” or fat or have broken edges. Although it can have wear from circulation.
So when in doubt don’t purchase and buy a graded and authenticated by (PCGS, NGC, ANACS, ICG) to learn the ropes of better identification.