There are two main ways to sew a hem - by hand, and by machine. Rolling a hem by hand is the most luxurious option; since each stitch is carefully controlled by manipulating fabric, needle, and thread, the majority of the work can be hidden inside the hem with only the faintest line of pinpricks visible from the front. The working thread travels over just a single thread on the front for each stitch in a well-done piece, and the tiny size helps it to be completely unnoticeable.
Light, soft and delicate, handkerchiefs with hand-rolled hems shouldn't have the very edge ironed too hard - it won't hurt them, but the soft roll of the hem looks best if it is allowed to have a bit of bounce.
Hemming a narrow rolled hem on a machine is a much faster process and is easier on the eyes then hemming by hand. The needle brings one thread down - the one threaded through the eye - and this is looped around the bobbin thread and pulled back up for the next stitch. This creates a small line of stitching visible from front and back, and the action of the machine rolls the fabric into a much tighter roll as it passes through.
Rolling a hem by machine does have some advantages, though - because it is a sturdier hem than the ethereal hand-rolled hem, it can be embellished! Stitching a fine satin cording to the hem makes one hell of a classy addition: 
We use invisible thread to hand stitch the cording to the handkerchiefs, so the line between linen and cord is sharp and defined from both sides. Only one join near a corner betrays that the cordage wasn't made square to start with.
Cording may be sharp, but for a softer look, there's nothing to beat handmade lace. We scored a dozen yards made in the old USSR - the Soviet government pushed hand crafts and promoted cottage industries, and many women bolstered their flagging incomes with a bit of lacemaking on the side. We make lace by hand using the same patterns and tools that (predominantly) women have been using since true lacemaking began at the end of the Middle Ages. We stitch it by hand, too:
Lacemaking - both the 'bobbin' or 'bone' laces that are created using dozens or hundreds of bobbins and the 'needle lace' created using nothing more than a needle to manipulate the threads are beautiful, exquisite and rich with symbols and history. They'll be the subject of many posts to come - but for now I'll leave you with a little glimpse of the work involved:
