\usetikzlibrary{backgrounds}
\begin{tikzpicture}[scale=1]
	\node (NW) at (-1,1) [rectangle,draw] {$\;\; \JW{n} \;\;$};
	\node (NE) at (1,1) [rectangle,draw] {$\;\; \JW{n} \;\;$};
	\node (SW) at (-1,-1) [rectangle,draw] {$\;\; \JW{n} \;\;$};
	\node (SE) at (1,-1) [rectangle,draw] {$\;\; \JW{n} \;\;$};

\begin{pgfonlayer}{background}	
	\draw (NW.-45) -- (SE.45);
	\draw (NW.-90) -- (SE.90);
	\draw (NW.-135) -- (SE.135);

	\draw[line width=4pt,white,opaque] (NE.-45) -- (SW.45);
	\draw[line width=4pt,white,opaque] (NE.-90) -- (SW.90);
	\draw[line width=4pt,white,opaque] (NE.-135) -- (SW.135);
	
	\draw (NE.-45) -- (SW.45);
	\draw (NE.-90) -- (SW.90);
	\draw (NE.-135) -- (SW.135);	
\end{pgfonlayer}
\end{tikzpicture}