Flowing Hair Half Dollar Going Bald?

Beautiful coin.

Chances are, any contamination of the type which worries you would already be visible on the coin, which doesn't seem to be the case here. Keep an eye on it over the next few months, using these photos as a baseline. If anything milky or green shows up on the surface of the coin, it needs to be cracked and soaked in acetone. I honestly do not believe you have any worries in this regard.

This is an extremely important coin whose value likely reaches five figures in "original surfaces" condition, and given the excellent appearance and PCGS Genuine endorsement, it probably hasn't lost a whole lot of value. Certainly no more than 20%, and likely much less. Attribute it for variety; some known varieties are pretty scarce and would cause an even lesser drop in value.

I'll research this one in my Overton and see if I can attribute it.

O-116, R.4. Not the rarest; not the most common. I believe I found this specific coin having sold at Heritage last year. If that was your purchase, I'd call it pretty well-bought. If not, let me know and I'll link the specific auction here.

Sweet half! Details look EF and it's certainly worth VF money even in a "Genuine" holder. PCGS would not have slabbed it if they thought problems would crop up later but everybody makes mistakes so as SuperDave suggests, "Keep an eye on it for a few months".

I identified the coin via the characteristic marks behind the eye. It sold for $5750 in August 2008, a price which I consider rather a steal for this coin:

http://coins.ha.com/common/view_ite...o=384&src=pr

You'll need to obtain a (free) membership to observe all the auction details; I recommend that to all members anyways because of Heritage's vast archive of high-resolution images.