Here is what stigma means…
G4742
From a primary word stizo, (to “stick”, that is, prick); a mark incised or punched (for recognition of ownership), that is, (figuratively) scar of service: - mark.
A clue may be found here...
Jeremiah 17:1
"The sin of Judah is written with a pen of iron, and with the point of a diamond: it is graven upon the table of their heart, and upon the horns of your altars"
How does one mark something?
With a Diamond tip.
What is Diamond?
Carbon...
6 Protons
6 Neutrons
6 Electrons
666
What does Carbon look like under a Microscope?
A "HEX"...
http://phys.org/news/2012-09-world-atomic-microscope-chemical-bonds.html
What else "pricks"?
A Sword.
What makes the *IRON* in a Sword sharp?
Carbon... as in Carbon Steel...
http://en.wikipedia.org/wiki/Carbon_steel
Note that the Carbon 666 tipped "pen" places the mark of *Sin* in the Heart.
Etc. etc. etc.
:sheep: