To make the blueberry swirl, combine blueberries, sugar, and lemon juice in a small saucepan. Simmer over medium heat, stirring occasionally, until the mixture becomes juicy and thickens slightly (about 5 minutes). Remove from heat and let cool.

Blend the cooled blueberry mixture until smooth. Strain through a fine-mesh sieve to remove seeds, if desired. Transfer to a bowl and chill until ready to use.

In a blender, combine frozen pineapple chunks, coconut cream, rum, sweetened condensed milk, and crushed ice. Blend on high speed until silky smooth and creamy.

If desired, rim chilled glasses with crystal sugar by moistening the rims with a wedge of lemon or lime and dipping them into a shallow dish of sugar.

Drizzle the chilled blueberry swirl inside the prepared glasses. Gently pour in the coconut-pineapple mixture, allowing the colors to swirl naturally.

Top each cocktail with a dollop of whipped cream and a few sugared blueberries. Add extra sparkle with a sprinkle of crystal sugar, if desired.

Serve immediately and enjoy your Tropical Blueberry Coconut Swirl Cocktail!