jQuery Grid Plugin - jqGrid

I try to store in a grid a Google map object in order to draw it later:

var figure = new GPolygon(...);

jQuery("#list3").addRowData(idz,{id:idz,name:figureName,objet:figure});

I retrieve the figure like this:

var fig = jQuery("#list3").getCell(idz,"objet");

and I try to draw it by:

map.addOverlay(fig)

but nothing happens !

Is it possible to store an array (?) in a cell of a grid ?