There are  two major  symbols that represent Kyokushin,
one is the symbol Kanku the other is the Kanji calligraph.

kanku

The KANKU originates from the Kanku kata.
The points of the Kanku represented by the forefingers
means the ultimate.
The wide part of the Kanku represents strength and power.
The center represents infinity and depth, 
the circle through the center helps unify mind and body. 
The circle surrounding the Kanku represents continuity.

 

The Kanji sign for Kyokushin, was written in a  calligraph way by  Japanese master in calligraphy Haramotoki. The original Kanji is in  blue and  seen on the left side at the jacket of Kyokushin karatekas.

 

 

 

  
Other symbols Kyokushin flag and Ichigeki