Here it is:
The Clover Seam Ripper!
I really like this seam ripper because it rips stitches so smoothly and easily--the tip is thin and pointy and the curved blade is very sharp. You do have to be VERY CAREFUL with it, though, because it's so sharp that you can end up cutting a hole in your fabric.
Ripping out seams isn't very fun so use a good seam ripper and you might not mind it as much.
HOW TO USE A SEAM RIPPER
It's not very hard to do but pay close attention to what you are doing so that you don't damage your fabric when ripping out stitches. When you find the stitch you need to rip, get under the thread with the tip of the seam ripper and then slide the stitch to the "U" shape of the seam ripper, which is the blade. This will "rip" your thread.
|Every few stitches ripped out.|
|Pulling the thread on the back side.|
You can open your seam and rip at the stitches between the fabric, but you risk ripping your fabric if you are too aggressive. Some might say this is the "wrong" way to rip out seams but I tend to rip this way more often because it goes faster. Sometimes this is the only way you can rip out the stitches because they are so small that you can't rip them out the other way.
|The stitches between the fabric.|
|Ripping out stitches.|
Do what works best for the seam you have to take out and just be careful.
Be careful to use the right stitch length (2.5 for a straight stitch) AND do not pull your fabric from the backside of the machine as you are sewing--this will give you uneven stitches! Uneven stitches aren't so pretty and are harder to rip out.