Ah... what a lovely thread. I'm so glad I found it! My favourite attire of all... While stockings are far less popular for everyday wear these days by the average female about town they have become much more popular I think in the last couple of decades as sexy wear and bedroom wear
Popularized also by porn-models.
I wear them as often as I can and spend far too much on them. Seamed stockings is the term you're looking for Zamdrist but these come in many different styles. The fake seam is common and rather cheaply made and mass produced and is merely a decoration. The other end of the scale are fully fashioned ones made in the style of the 1930s and 40s on mechanical looms and still produced authentically in at least Britain and France by specialist hosiery companies. These have all the parts playing an intrinsic role in the stocking's construction, the backseam is actually where the flat silk or nylon mesh is joined with a proper 'seam' of stitching into the tube shape that makes up the leg and you'll see a small cut-out hole in one layer of the top welt (the usually darker top that goes around the thigh) at the very top of the seam. This style of stitching has it's weak points at the toe, sole and heel and so you will often find the characteristic reinforcing at these points similar to the doubling of the layers at the welt.
Even this reinforcing comes in various styles: in Cuban heels it has a horizontal cut off about an inch wide above the heel; in French heels it tapers to a point; in European heels it tapers to a narrower horizontal cut-off than Cuban heels but isn't tapered like the French heel. I think there are a couple more and all come with and without reinforced soles.
You can also get the traditional toe and heel reinforcing without seams... the variations are endless.
And tights (pantyhose in America), stockings of all kinds and socks are all 'hosiery'. Namely an undergarment worn to keep the skirt-wearing female warm or to make the legs look sexier. A hosiery department in a department store will stock all kinds - pantyhose, normal mass produced stockings, seamed stockings, hold-ups or thigh-highs which have an elasticated or silicon band within the welt to keep the stocking up without the use of a suspender belt (garter belt in America) as well as ordinary socks of various lengths.
I am something of a fan of the subject, and a fetishist for very expensive hand stitched fully fashioned seamed stockings.
And yes, Secrets In Lace is one of the best websites for them, they have a huge range and I don't care to think how much I have spent with them over the years...