I found that the best way to get the seeds of basil is to wait until the seeds are ripe (turn completely black), but before the calyx, or whatever that thingy the seeds are in is called, turn brown and papery (you should have quite a bit of time). They you just pick the calyx (or whatever) of the stem (careful not to drop the seeds inside, as they can be fairly loose already), then gently squeeze from the back, rubbing a little, until all four seeds (or however many manage to ripen) fall out onto a piece of paper or your hand. I have never gotten any chaff with basil seeds. You won't hurt the seeds. They seem to be designed to be able to take quite a bit of rubbing and are quite tough, as long as you don't purposefully crush them.

Or if you get powdery stuff and can't separate the seeds, try using two pieces of tissue or paper towel. Put everything on one, then slide them at a gentle angle to the second piece. The larger seeds should roll off to the other piece easily, leaving the chaff. If you have some chaff left, repeat. After a couple of times, the seeds should be easy to pick off.

I crush the seedheads then put them thru a flour sifter from the Dollar Store. Shake the sifter,don't crank the handle otherwise the seeds might be destoryed. Works great on all small seeds and gets most of the chaff out.

PP