I made a Madhur Jaffrey's recipe and it seems fine :-
1 tablespoon cardamom seeds
A 2" stick of cinnamon
1 teaspoon black cumin seeds
1 teaspoon whole cloves
1 teaspoon black peppercorns
1/4 of an average sized nutmeg
Place all the ingredients into a clean coffee grinder (or any other spice grinder) and turn on the machine for about 30-40 seconds, until the spices are finely ground. Store in a small jar with a tight fitting lid.
Failing the "do it yourself," Sharwood's do a pretty need Garam Masala.