This blue raindrop-patterned pocket square is versatile and pairs effectively with several classic suit colors:
Recommended Suit Colors
Black: A black suit provides a sleek, high-contrast backdrop that allows the various shades of blue and white raindrops to stand out sharply.
Navy Blue: For a more subtle, monochromatic look, pairing it with a navy suit creates an intriguing contrast. The different blue tones in the pattern will complement the suit's deeper hue.
Gray and Silver: Neutral tones like gray or silver offer a sophisticated, understated aesthetic that whispers rather than shouts.
Cream or Tan: For a modern or more casual style, lighter neutrals can highlight the brighter blue tones in the pattern. 
Styling Tips
White Shirt: A crisp white shirt is a safe and elegant choice that will make the pocket square the focal point of the outfit.
Blue Shirt: Pairing it with a blue shirt can also work well; the specific shade of the shirt can help guide how prominent the pocket square appears.
Fold Choice: For a pattern like this, a puff fold or a straight fold can effectively showcase the repetitive raindrop design.