Wash, stem and stone the cherries. Weigh 1 kg of pulp. Mix well with the preserving sugar in a large saucepan and let steep for about 3 hours. Roast the almonds in a pan until golden brown. Sprinkle sugar over it and let it caramelize. Immediately remove the almonds and let them cool. Bring the cherries to the boil while stirring, let them simmer for 4 minutes. Stir in the almonds and grappa and immediately pour the jam into prepared 300 ml glasses. Seal and let cool upside down.