Chill the kombucha, lemonade, and sparkling water in the refrigerator for at least 2 hours before mixing; the colder each one starts, the less ice you need later.

In a 3-quart punch bowl or beverage dispenser, pour in the lemonade and raspberry kombucha. Stir gently with a long spoon for about 10 seconds, just until combined.

Add the fresh raspberries and lemon slices to the bowl; they float and tint the liquid a soft pink within a few minutes.

Pour in the sparkling water right before guests arrive and stir once, lightly, to keep the bubbles.

Lower the ice ring into the bowl so it floats rather than sinks to the bottom.

Serve within 2 hours of adding the sparkling water for the brightest fizz; it fades fastest once the kombucha's own carbonation joins it.