Lightly process the almonds and 1 oz / 30 g crystallized violets in a blender or pound in a mortar. Mix in the sugar, flour and salt. Whisk the egg whites, and fold into the dry ingredients. Line baking sheets with rice paper, and drop teaspoons of the mixture on to it. Flatten slightly with a wet teaspoon or palette knife, and place a crystallized violet in the centre of each. Bake on the middle shelf of a preheated oven at 150°C / 300°F / Mark 2 for about 30 minutes. The biscuits should not brown, as you want the violet colour to show through. If you take the biscuits out of the oven at this stage and allow them to cool on wire racks, they will still be slightly chewy inside when cold. To dry them completely, turn off the oven, place the baking sheets of biscuits on the floor of the oven and leave them for another 30 minutes or so with the door slightly ajar. Remove and cool on wire racks.