What not to do...
Or at least, it's about some of the gift rosaries I've made that have some feature or other that is certainly not documentable as medieval, in my current state of knowledge.
First, you should ignore the elephant on this next set of beads: it's there because the recipient likes elephants. ;)
Other than the elephant, this is an attempt to construct a set of beads that might be appropriate for a Viking. This isn't quite as lunatic as it sounds: a good many of the Vikings did become Christians. However the peak centuries of what are popularly called "the Vikings" were a couple of hundred years before Christian prayer beads became really popular, so these are probably an anachronism. (And so is the style of the elephant pendant.)
I was inspired to create these by the marker beads, which are some sort of low-grade carnelian with silver caps. The end bead is a larger carved wood bead with more or less matching caps, and the pendant is a "knotwork" cross (though it doesn't look much like actual Norse or Irish knotwork). The small beads are carnelian.
This next set of beads has two features I wouldn't recommend if you're trying to make a set of documentably medieval beads. As I've mentioned before, I don't think I've seen any clear examples of paternoster or rosary beads with Ave beads (the small ones) of two colors alternating. I certainly haven't seen any actual surviving ones that are that way. I wrote a bit more about the doubtful evidence from paintings and woodcuts in my post on the Cabbage-Noster.
The other feature I don't recommend here is the faceted marker beads. While the carving and faceting of beads by hand was certainly possible in the Middle Ages, it was expensive, and not something that was normally done to glass beads: I don't think faceted glass beads became really common until machines were invented to do it rapidly and in quantity. I also don't think this particular style of faceting is at all likely for medieval beads. I bought these black faceted beads years ago and am finally using up the last of them.
Note: if you're wondering about the funny-looking background of some of these, I photograph most beads on my scanner, using a piece of synthetic white "fur" as the background. I'm in too much of a hurry at the moment to do the meticulous retouching to eliminate the shadows of the "fur.")
My third example today is of something that I actually think is plausible, though I can't prove it. This rosary was made for someone who wanted something in the style of "Henry VIII before the break with Rome." The flat, rose-shaped brass beads were something I ran across in a bead catalog, and I quite like them. The rose symbolism is quite appropriate for that period in English history -- a heraldic badge used by Henry VIII and his first wife Catharine of Aragon was a round symbol made from half a rose (for Henry) and half a pomegranate (for Catherine). We know that marker beads for rosaries were made in all sorts of shapes, some of which may also have heraldic significance, and we can be fairly sure that some marker beads were flat rather than round, so I was quite pleased to find these. Of course aristocratic beads like these would more likely have had actual gold markers; I don't know to what extent gold jewelry was imitated in brass in the Renaissance.
I'm much more dubious about the leaves I added to the same rose-shaped marker beads in the next rosary. We do know that at times the gauds (marker beads) were set off from the other beads by what might be called "spacers," smaller beads that are mostly decorative and don't "count" as part of the beads used for prayer. (Germans call them "Zwischenperlen," which I still think is a lovely word.) I was given these little leaf beads (also brass) as a gift, and my modern taste says they set off the rose beads nicely. But I can't document anything like this. All the Zwischenperlen I have seen in historical beads are little round, oval or flattened oval beads.
Like King René of Anjou (1409-1480) I make rosaries as a hobby. Unlike René, however, I try to make mine in the style of a historical period quite different from my own. ;) It's an interesting exercise, but it almost always means making some compromises with history, since (for one thing) for the most part we don't have exactly the same materials people in the Middle Ages had to work with. The round glass beads I use so often, for instance, are made by pressing -- a 19th century invention -- rather than being individually hand-wound on a mandrel. And we are not medieval people ourselves, so what seemed appropriate or attractive to them may or may not seem that way to us -- and vice versa.
These particular sets of beads show stronger tendencies than (I hope) most of what I make to "bend" the unwritten rules of medieval style in order to produce something I thought the recipients of the gifts would like. They're still fun, and making medieval rosaries as gifts is an incentive to research and debate the issues that come up in making them.