How do I change bar chart color based on value?

[ESPrioleau]

I've tried:

<option name="charting.fieldColors">{"Blocks_Blocked":0x006400, "Allowed_block":0xCCCC00, "Allowed":0xCCCC00}</option>
        <option name="charting.chart">bar</option>
        <option name="charting.chart.showDataLabels">all</option>
        <option name="charting.chart.stackMode">default</option>
        <option name="charting.drilldown">all</option>
        <option name="refresh.display">progressbar</option> 

but this isn't working, if I do this, it changes the colors, but not based on value:

<option name="charting.seriesColors">[0x006400, 0xCCCC00]</option>