Vairette is probably a variation of Vairet, which is a French surname going back to the Old French word vair, which originally meant "variegated". So it was either a nickname for someone with a blotchy complexion, or for someone who had the habit of dressing in clothes that were multi-colored. As explained in the remarks below about Cinderella, in medieval France the word vair also was used for a type of multi-hued squirrel fur imported from Russia. The -et or -ette would indeed be a diminutive, so the original connotation of the surname would have been "small/cute/young person with a variegated appearance".
The above information is from Hanks & Hodges's A Dictionary of Surnames.
This message was edited by the author on August 24, 2006 at 2:23:57 PM