MFC and Akro made true oxblood on purpose from recipe. Akro obtained the formula illegitimately from MFC.
I'm hearing the possibility discussed that Alley made it on purpose also. I don't know about that. I think it might have appeared accidentally in other marbles, when the right chemical and heat conditions occurred. But of course most of what is called oxblood on eBay ain't.
By true oxblood, I refer to the oxblood discussed at Brian Graham's site here:
http://www.canalfultonglassworks.com/melting_oxblood_glass.htm
(oh, and of course, you are showing true ox in your photo)
Jabo in the past few years has made oxblood with the help of aventurine, which is chemically related to oxblood, as discussed on Brian's site.