Church sale find of 2,300 Year Old Coin of Alexander The Great's Father

I came across a church sale recently and one of the dealers selling costume jewelry had this coin on a cheap zinc-type chain. He was asking $10.00 for it and I thought that it would be fun to find out more about it even if it could be a fake. It had a triple wire bail affixed to it so it did look a little unusual for an old coin but the images on it were quite clear. Liking odd things, I bought it and brought it home to do some research on the internet. It took me at least 5 hours to realize that the image of the Horseman on the reverse was actually of Philip II, King of Macedonia who reigned from 359 to 336 BC. The Obverse was an image of ZEUS. Apparently many coins of Philip II on a horse facing right in different poses were minted but the ones with his horse facing left are quite rare. There are no known forgeries or copies of this coin so it's quite probable that it's the real thing. The Silver chain on it now is one that I added. I will be adding a link to a similar coin going for auction on July 7, 2016.
I wonder how, by the fact that it has been made into a pendant/medal by adding the bail, it will affect the value of this old coin? Still a nice conversation piece and an interesting topic for us CWers. BOB