When working in rounds without turning, the neatest and seamless way to fasten off without leaving an unsightly bump is by working an “invisible join”. Here is how it can be done step by step.
Step 1: Work you last stitch if you have been crocheting in a spiral. If you worked in joined rounds, once you have worked the last stitch of the last round, do not join it with a slip stitch to the start of the round. The circle below has been worked in spiral rounds:
Step 2: Clip the yarn, leaving about a 8″ (15 cm) tail. Then pull on the last loop on the hook until the tail pops out:
Step 3: Thread the tail onto a yarn needle. Insert the needle underneath the top loops of the first stitch of the round:
Step 4: Pull the yarn through and insert the needle into the stitch the tail came out of. Pull the tail just enough so that the formed loop mimics the size of the top loops of the rest of the stitches:
Weave in the tail securely and you are done:
What happens here, however, is that the new loop creates an appearance of an extra stitch. If you’d rather not see that happening, you can work Step 3 differently: instead of inserting the needle underneath the top loops of the first stitch, skip it and insert the needle underneath the top loops of the second stitch of the round:
It still looks tidy enough: