You could create an additional attribute of type multiple select, call it 'colour detail' and then give it values of 'blue', 'white' and 'stripes'. Perhaps put stripes in an attribute called 'pattern' that can be 'plain', 'check', 'corduroy' etc
Note that the default way Magento searches is 'OR' so a colour called 'Blue White Stripes' will create a search hit if a user enters just 'blue' into the search box. But most theme developers override the Magento code(see second answer) to make Magento search 'AND' because with the default 'OR' a user who searches for 'blue shirt' will see 'blue trousers', 'blue shoes', 'blue shirt', 'red shirt', 'white shirt' because they all match 'blue' OR 'shirt'.
So I recommend the additional attribute - particularly if you want it to be displayed and filterable in the search results.