Original designs and patterns from Squares and Buttons
A navy blue suit or a tan/beige suit would go well with this pocket square.     
Navy Blue Suit: The dominant blue in the pocket square makes a navy suit a natural, classic pairing. The magenta accents provide a subtle contrast that makes the outfit interesting without being overwhelming. 
Tan or Beige Suit: A tan or beige suit would complement the warm, copper-toned background of the pocket square. This creates a sophisticated, warm-weather look. 
Charcoal Gray Suit: For a versatile option, a charcoal gray suit provides a neutral canvas that allows the vibrant blue and copper colors of the pocket square to stand out.              
Ultimately, the key is to ensure the suit color harmonizes with the colors present in the pocket square without matching the exact shade of the tie (if one is worn).