In a large non-reactive pot, combine the granulated sugar, apple cider vinegar, drained crushed pineapple, turmeric, celery seed, garlic, and cayenne pepper.

Bring the mixture to a rolling boil over medium-high heat, then reduce the heat and simmer for 5 minutes to dissolve sugar and infuse flavors.

Add the sliced jalapeño rounds to the pot and increase the heat to bring back to a boil.

Reduce heat and simmer the jalapeños for exactly 4 minutes until they lose their bright green color and soften slightly.

Using a slotted spoon, transfer the jalapeño slices and pineapple solids into sterilized half-pint canning jars, leaving 1/2 inch of headspace.

Increase the heat on the remaining syrup and boil vigorously for 6 to 10 minutes until it reduces to a thick, honey-like consistency.

Pour the hot syrup over the jalapeños in the jars, maintaining 1/4 inch of headspace.

Wipe the rims of the jars with a clean damp cloth, apply lids and rings, and process in a boiling water bath for 10 minutes.