Combining already socketed gems?

It's the game's subtle way of saying you can't combine gems anymore. You will find more gems as you play and they will become more powerful as you progress. You can't combine gems to make better gems.

You can't combine gems that are already socketed. Socketed gems are locked into the gear you put it into. You can either choose to recover the gem or recover the gear from a vendor in town.

You can't combine gems in Torchlight 2. You can socket, remove while sparing gem and destroying item, remove while sparing the item and destroying the gem. You can't combine, but I'd still save them for the appropriate gear, instead of just throwing them in any old hole.

I have been combining my low level gems (3 at a time) to make stronger gems. So I am a bit confused why the game says not to hoard them.