2 cups (tightly packed) fragrant edible rose petals
In a small saucepan, bring the sugar and 1/2 cup of water to a simmer over moderate heat, stirring until the sugar is dissolved. Set aside until slightly cooled but still very warm to the touch. Stir in the rose petals, packing them into the syrup as they wilt. Using a rubber spatula, scrape the mixture into a glass measure or small heatproof glass bowl. Cover with plastic wrap and set aside to steep at room temperature for at least 6 hours, or refrigerate overnight.
Pass the syrup through a coarse strainer, reserving the strained rose petals. Pour the syrup into a small saucepan and boil over high heat until reduced by half, about 4 minutes. Se aside to cool slightly.
In a food processor, combine the syrup with the reserved rose petals and process until the petals are coarsely ground. Scrape the mixture into a glass jar and let cool.
The jam will keep refrigerated for up to 6 months.