document.observe("dom:loaded", function () {
    var selectIds = ["ring_size", "bracelet_size", "chain_size"];
    selectIds.forEach(function (multiSelectId) {
        var multiSelect = $$("#"+multiSelectId).first();
        if (typeof (multiSelect) != 'undefined') {
            selectAllOptions(multiSelect);
        }
    });
});
function selectAllOptions(obj) {
    for (var i=0; i<obj.options.length; i++) {
        obj.options[i].selected = true;
    }
}