Here is a vibrantly toned 1809 Capped Bust Half Dollar in PCGS XF45.  It comes with a manilla envelope where presumably it was stored for a substantial time period and where it likely acquired its gorgeous toning.  This envelope is part of this bust halves history and is included in the offering.  The information on it is interesting.  It makes claims to AU50 for grade which we do not disagree with, and that it is an O-102a(?) with the XXX Edge variety.  In 1809 the US mint used several different Edges, including XXX or IIII in the lettering, and even a plain edge, along with the normal edge with normal lettering.  Unfortunately, right where the XXX should be on the edge of the coin, the PCGS prongs are covering it.  Whomever had it in the envelope seemed to determine it was indeed the O-102a with XXX edge, but in its present holder than cannot be confirmed.  The difference between the O-102 and the O-102 a (die state progression), is not very clear as the guides we have show that they pretty much overlap in terms of cracks etc, and certainly the examples of each on PCGS Coinfacts look the same for the ‘later’ die states of the O-102 as the O-102a.  So this needs a person with vast experience to determine whether it best fits into the O-102 or O-102a categories.
 
Further, From Coinfacts:
 
"The XXX edge is one of four edge varieties found on 1809 Half Dollars. These include: XXX edge, IIIII edge, plain edge, and the so-called "normal" edge (with "a pseudo engraved in front of FIFTY" - per Overton). Several varieties comprise the XXX edge: O-101, O-102, O-108a, and O-110. Curiously, different die states of the same variety can have different edges. For example, O-102 is found with the XXX edge, but O-102a is found with a plain edge. Similarly, O-108 has a IIIII edge, but O-108a has a XXX edge. Be sure to examine the edges of your 1809 Half Dollars carefully - it is quite possible that you could discover an unknown edge usage where it is least expected."
 
This adds intrigue to several of the 1809 die marriages including this one. But a little confusing and would have to be cracked out to determine whether it has the XXX edge or not and a final word from a true Bust Half aficionado as to whether it is O-102 or O-102a.  
 
This coin is uber pq in terms of eye appeal resulting from the vibrant and classic aqua to amber toning progressions on each side.  This, combined with the interesting issue of whether this is a normally lettered edge or includes the XXX makes this coin special and a rare find. 
 
PCGS Cert. #50765906