[phillryu]

When I create icons, I use Photoshop to create the image, usualy at a larger size, then use Apple's icon builder to put together the icon. However, the icon tends to be jaggy on the desktop, while other icons I have seen scale perfectly. Is there a way I can prevent this?

[Adam Betts]

I usually flatten the layers then resize the icon in Photoshop first before exporting them to any icon editor apps.

[OptimusG4]

Or you can use the (expensive) IconBuilder plugin from IconFactory.