All series types expose a ColorField property that you can use to specify a column in the data source from which the color for each item in the series will be taken. You can find a good demo of how this works in the Conditional Item Colorization Demo.
The color must be passed as a string in the data source and its format can be either a color name (e.g. "red", "green", "blue"), or a hex value (e.g. "#cccccc", "#ff00ee", "#123456"). This functionality became available in Q1 2013. The exception are PieSeries and DonutSeries which expose the property since the release of the control.
If a cell from the data source column that stores the colors has an empty string, the chart will use the default color for the corresponding series item. This means that a special string is required only for the series items that must be colored differently. This is also illustrated in the Conditional Item Colorization Demo
The color of the segment from PieSeries/DonutSeries/FunnelSeries and the corresponding legend's square indicator is determined from:
The BackgroundColor property of each PieSeriesItem/FunnelSeriesItem for a non-data bound scenario.
The values in the data source field that is specified in the ColorField property of the series for a data bound scenario.
You can define a common color for all of the items from each BarSeries/ColumnSeries/BubbleSeries through the [Series Type].Appearance.FillStyle.BackgroundColor property. This color is also used for the legend's square indicator of the corresponding series.
You can also modify the color of each item within a series through:
The BackgroundColor property of each CategorySeriesItem/BubbleSeriesItem for a non-data bound scenario.
The values in the data source field that is specified in the ColorField property of the series for a data bound scenario. If an empty string is met the item will use the color specified in the main series configuration.
You can define a common color for the entire series that will be used for the lines and the color fill of the area (where applicable) through the [Series Type].Appearance.FillStyle.BackgroundColor property. This color is also used for the legend's square indicator of the corresponding series.
You can define a common background and border colors for the markers within an entire series through the BackgroundColor and BorderColor properties of the [Series Type].MarkersAppearance tag.
Setting a custom color for an item changes the markers's border color as well as the background color for the tooltip and the marker on hover.
The Conditional Item Colorization Demo with randomly generated data shows how you can customize the data source, so that items with given values have custom colors. Similar logic can be extended for other databinding methods, e.g., using a programmatic DataTable or a column from a declarative data source like the SqlDataSource in case the database already has the desired information.