How can one open unopened pistachio nuts?

Here’s a link to instructions on how to open a pesky pistachio nut.
Step 1
You should always use the right tool for the right job, and lucky for you, you already have a whole pile of the right tool already near by when you are eating pistachio nuts.
Grab a discarded ‘pistachio nut shell half’, and stick the top of the small end into the partially-opened pistachio.

Step 2
Now Twist Like You’ve Never Twisted Before
With the shell top inserted into the crack, twist the shell half like you would turn a screwdriver. Clockwise or counterclockwise directions both work equally well. As you twist, the shell will separate with a loud report as if by magic.

Step 3
You did it. Sure, anyone can open a pistachio with a LeatherMan, hammer, or laser cutter. But without using any of those traditional pistachio-opening tools, and without risking injury of your fingernails, teeth, or your pride, you beat the pistachio at its own game. You got to the prize. Now eat it. Savor the morsel that was previously unreachable by humankind.

Next time you’re sitting around with friends eating pistachios, show them this trick…and remember that you learned it on Instructables.

For nuts that are completely sealed, I suggest using a nut cracker to apply pressure to crack the nut- or the blunt side of a meat cleaver to tap the sealed edge until it cracks.

use a nutcracker

Use a nutcracker, or a pair of pliers.