If I\'m using the default Highcharts tooltip, it displays a circle the color of the chart data (the light/dark blue circles at http://jsfiddle.net/WOUNDEDStevenJones/mpMvk/1
You may use:
> $.each(this.points, function () { > s += '\u25CF' + this.series.name + ': ' + '' + this.y + ''; > });