A Clover Seam Ripper is a must in every sewing room. I've had various Seam Rippers but have found this one to be my favourite.

The point is really sharp so it will easily get into and cut through small stitches.
Great for cutting threads under buttons.

It has a larger handle than most which fits snuggly into the palm of your hand.

Cut effortlessly through any seam with this strong, sharp cutter from Clover.