This is special kolam for the occasion of Karadiyan Nombu.
You may be aware Karadaiyan Nombu, or Savitri Nonbu Vritham, is a Tamil observance in which married woman prays for the well being and long life of her husband. Karadaiyan Nombu 2014 date is March 14 and time of breaking of fast and to wear Saradu is between 6:30 PM and 7:00 PM Karadai is the name of a unique nivedya (holy dish) prepared on this day. Nombu means Vratam or upvasam (fast).
Hope it has come out well...!