[NTG-context] how to insert symbols into document?

[Csikos Bela]

Hello context users:

I would like to insert symbols into my document, especially black-diamond and losenge
symbols. I read symbols page at contextgarden but still don't know how to do it.

I also tried \showsymbolset[was] etc but the symbols but I did not find these (and many
other symbols either) in the output pages.

I found that symb-imp-mis.mkiv file defines this symbol (line 49) but I don't know how to
make it show. Do I have to load specific symbol fonts? If yes how can I find out which font has the given symbols? 

What I tried so far included:

% begin code
\usesymbols[imp-mis]
\starttext

◆

\blackdiamond

\symbol [blackdiamond]
% end code

None of these show anything.

Thanks in advance,

bcsikos