Lisa Featherby, Gourmet Traveller Food Editor, writes:
"The business of gelatine has left a lot of people confused and frustrated recently.
Gelatine comes in many different grades of leaf as well as powdered, and although you would think each company producing it would make each grade of leaf or powder to a set weight or setting ability, this is not the case.
The best advice is to use the strength of gelatine recommended in the recipe. If you can only get your hands on a different type, then I suggest following the instructions given on the packet - as most packaging has information on how much liquid each leaf or teaspoon of powdered gelatine will set.
Another good reference comes from Stephanie Alexander’s book, The Cook's Companion (latest edition), where she states that through her testing she found 1 leaf of titanium set 1 cup of liquid, whereas it took 3 leaves of gold strength to do the same. There is no guarantee this will work for you, though, so be prepared as it may just be a case of trial and error on your behalf. One last thing to consider is that varied thickness and viscosity of any liquid you are setting may need different levels of gelatine to produce the right texture in the end result. For instance, the mascarpone mousse in the recipe mentioned requires less gelatine than the mango jelly layer due to its thickness.
Good luck and hope it all gels!"