I normally use organic golden granulated or caster sugar in my cooking, as it is slightly less refined than white sugar. In my flower desserts, however, I always use refined sugar as I want nothing to detract from the pure colour of the flower extracted in the syrup, cream, cordial or jelly.
The best sugar for making jams and jellies is that with the largest crystals, as this dissolves slowly, minimising scum and producing a nice clarity in the finished product. If it is available, use preserving sugar, which has extra large crystals. Cooks in the US and other countries where preserving sugar is not available can use granulated sugar, which is an excellent all-round sugar, whatever preserves you are making. Jam sugar, which contains pectin and citric acid, is a great boon when making jams and jellies from ingredients such as flower infusions, strawberries and figs which lack or are low in pectin, as the preserve always sets when you follow the directions on the packet. Where jam sugar is not available and the recipe does not call for an extract of cooked apples, use liquid or powdered pectin, following the instructions on the label.