The banknotes used on screen in Firefly episodes are the brainchild
of Prop Master Randy Eriksen. Randy designed the banknotes and
printed them on the computer in his office. They are printed on
translucent 'vellum' art paper and are only printed on one side,
the design showing through the translucent paper to the other.
There are four basic denominations:
Purple $10, Green $20, Purple $1200, Green $1200
There are a couple of notable variations:
Some smaller notes were printed on plain, opaque paper
(very few in number)
There is a very rare non-denomonational green note printed
without any value on it. I know of only two copies.
The other notable variants are the '47' notes, also in the
'Safe'money bag. 47 is Randy's lucky number and is the most
common randomly occurring number in nature...apparently.
Mouseover images to enlarge.