String.Format question

Hi,
I am returning values from a database, these numbers can be negative or positive. If negative they need to be contained within brackets and be red, how can I achieve this using String.Format?
example of current line..
decimal amount = String.Format("{0:0,0.00}", dataReader.GetValue(3));
needs to return (1,300.48) in red  and 1,300.48 in black if positive...
Thanks
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