[Solved]-Conditional coloring of marker in box plot in highcharts-Highcharts

You could check your data before using it in Highcharts and add color value for each point if requirements are met. Example: http://jsfiddle.net/nshkf75s/

Relevant part of code:

    series: [{
        name: 'Observations',
        data: [
            [760, 801, 848, 895, 965],
            [733, 853, 939, 980, 1080, 'orange'],
            [714, 762, 817, 870, 918],
            [724, 802, 806, 871, 950],
            [834, 836, 864, 882, 910]
        ],
        keys: ['low','q1','median','q3','high','color'],
        ...