I believe that there are around five of these original cobalt masons.  There are many reproductions of various sorts, mostly either midgets or half gallons.  I'm not really sure where these five came from.  I'm assuming they were all found at one source but that's just my assumption which may very well be wrong.

This jar has a lot going for it.  There is no set of jars that has gathered the same attention as jars embossed "Mason's Patent Nov 30th 1858".  There is an entire book devoted to them which is planned for publication.  This attention means that oddities in these jars bring top dollar and in a hobby where "color is king", this cobalt represents probably the most desirable oddity.  Many Mason oriented collectors would probably call this their most desired jar.