[XeTeX] color some Hebrew vowels

[Lorenz Haas]

Hi,

I want to color several letters and vowels in Hebrew therefore I have defined 
some shorthands:

\usepackage{bidi}
\newfontface\HebFont[Mapping=tex-text,Script=Hebrew]{SBL Hebrew}
\definecolor{hebcol}{rgb}{1,.1,.1}
\newcommand{\he}[1]{{\RL\HebFont #1}}
\newcommand{\hem}[1]{#1}
...
\he{ל\hem{וֹ}מ\hem{ֵ}ד} % this is "lomed" with וֹ and ֵ   colored.


With that definition of \hem the vowels are places correctly but as soon I add 
the "color option", the vowels shift leftward:

\newcommand{\hem}[1]{{\color{hebcol}#1}}

How can I prevent that and also that only the vowel or letter are colored?


Any hints are welcome, thanks
Lorenz