WITH PotentialDates (d) AS (
    SELECT '2013-01-08 15:44:12.2081606 +05:30'
    UNION ALL SELECT '2013-01-08 15:44:12.2081606'
    UNION ALL SELECT '2013-01-08 15:44:12.208'
    UNION ALL SELECT '2013-01-08'
    UNION ALL SELECT 'YYYY-DD-MM HH:MM:SS.mmmmmm'
    )
SELECT IsDate=ISDATE(d)
    ,PATINDEX('[0-9][0-9][0-9][0-9][-][0-9][0-9][-][0-9][0-9]', LEFT(d, 10))
    ,ISDATE(LEFT(d, 23))
FROM PotentialDates

DECLARE @String VARCHAR(50) = '2013-01-08 15:44:12.20848489 -05:30'
IF
	PATINDEX('%[A-Z]%',@String) = 0
BEGIN
	SELECT
		CASE WHEN LEN(@String) = 10 THEN 'Date'
			 WHEN LEN(@String) = 23 THEN 'DateTime'
			 WHEN CHARINDEX('+',@String) > 0 THEN '+ Offset'
			 WHEN CHARINDEX('-',REVERSE(@String)) <=6 THEN '- Offset'
		END AS WhatIsTheDataType	 
END
ELSE
SELECT 'You have not supplied a valid date'