numToChar with socking great numbers

[Richmond]

So, I found that the Unicode Consortium puts a smiley face at address 
1F600 (hex) = 128512(decimal),

but when I go

set the useUnicode to true
set the unicodeText of fld "feeld" to numToChar(128512)

I get a nifty Bengali char that returns 62976, which is, rather predictably,
128512 - 65536 (or 256 x 256).

And, while that is all rather jolly in terms of base 16 Maths is doesn't 
do much for
my urge to propagate smiley faces all over the shop.

Doing this:

set the useUnicode to true
set the unicodeText of fld "feeld" to numToChar(65536+62976)

gives me numToChar(62976)

Now I assume (dangerous business that) that there is a way (???) to get 
hold of the characters
in the higher planes (i.e. above 65536) of the Unicode font system, but 
don't know how to do that.

Does anybody know?

Richmond.