Amount: 60, radius 4.9, threshold 4.  The amount is sometimes raised to about 100.  The threshold will help remove noise.

*sometimes* you WANT to oversharpen an image to get some pretty cool effects.  These have been heavily oversharped by moving the amount and radius waay up (amount was maxed out), but leave the threshold down low:

Before and after lily:

It yields a very graphic effect if you have a strange little photo, like Tahichi eating his Sunday morning pancakes in his ritual uniform of silk pjs an leopard print fez:

And of course, if you use it on your clay images - it gives you a strikingly graphic image, but still maintains while preserving the design of the clay: