Select ripe quinces. Cut them into equal slices of 1/4″ (0.5) cm wide. Peel and clean them. Place the cleaned slices in cold water, in order not to darken. Blanch them for 3-4 minutes in boiling water and then put them back in the cold water.
Prepare a thick sugar syrup from the sugar and water. Drain the quinces well of their water and place them in the syrup. Boil on high heat until the syrup thickens and the quinces become transparent. 2-3 minutes before removing the jam from the heat, add the tartaric acid and geranium.
Distribute the ready jam in wide containers, to cool quickly and keep its amber color. Then pour it into jars.