Pit the cherries and remove the stems (you can save the stems and dry them for tea). Cherries have to be ripe but firm. Softer cherries can be used to make jam.
Mix cherries in a mixing bowl with 2 cups of sugar. Cover with plastic wrap and let chill for minimum 4-5 hrs. I usually let them chill overnight. Cherries will absorb the sugar.
Add sugared cherries and 1.5 cups water in a pot. Turn heat on and once water boils, lower heat to simmer or low. Add the last cup of sugar. Let cook on low heat for 1 hour.
Leave the preserve cool down for few hours.
Return the pot on the stovetop. Turn heat on and once the preserve starts cooking, low heat again to low. Let cook until there's very little syrup left, usually another hour or so. Add lemon juice and zest halway through.
Use proper canning techniques for bigger batches. This recipe produces about 16 ozs of gliko (1 jar).
Notes
Calories are estimated assuming 1 serving is 1 tbsp. But believe me it's hard to stop at just 1 tbsp. Fair warning:)