\documentclass{minimal}
\def\pgfsysdriver{pgfsys-tex4ht.def}
\usepackage{tikz}
\begin{document}
\centering
\begin{tikzpicture}
	\foreach \x/\y/\color in {1/2/red,3/4/green,5/6/blue}
	\shade [ball color=\color] (\x,\y) circle (\x/\y);
\end{tikzpicture}
\end{document}