Just for fun while we were in Bruges and Ghent, I started noting the different styles of rosaries that were shown in the late-period paintings. It gave me something to focus on while studying the rich and startlingly clear and crisp images of the 'Flemish Primitives', which is the collective description for those painters who worked around the same time as Van Eyck in the late mid-15th and early 16th centuries.
So here are my findings. All of the rosaries I noted were rounds (rather than straight strings).
Unfortunately no cameras, bags, jackets, etc etc were allowed into the Groeningmuseum, so I had to hunt up the images online afterward in Vlaamsekunstcollectie. My Flemish is crap, so bear with me (search is in English, descriptions are in Flemish).
ETA: sorry about the crap links. Use the advanced search from the link, and enter the inventory number to find the pieces I saw.
You can zoom on these images, but the enlargements aren't great - too low-res.
Master of the Holy Blood, active 1500-1520, inventory no 1991.GRO0008.I
Madonna with SS Barbara and Catherine (allows zooming, in popup window)
Rosary of coral beads on long cord, hanging from the knot of her blue sash, over a black gown.
Agnus Dei medallion at the bottom
6 decade beads visible, and they're filigree beads (look like 2 halves of a cast bead maybe?) about size of a fingernail
Jan Provoost, 1462-1529, inventory no. 0000.GRO0216.I-0218.I
Death and the Miser (2 two-part images) (a miser trying to give Death an IOU, very good, then the donor and his wife at prayer, with a bishop and St. Gudula watching over them)
Very long rosary of coral beads, about 8 decade beads of shiny gold, though possibly more, because the top of the rosary is hidden by the woman's gown. HUGE gold cross at the end, with pearls on pins in the ends and the corners of the cross, and in the corner of the arms of the cross.
Gerard David, active 1502-1508, inventory no. 0000.GRO0035.I-0039.I
Baptism of Christ (triptych)
This is a large triptych, with Christ being baptised in the middle, and the donor with his sons on the left side, and his wife and the daughters on the right side, both sides being watched over by handy saints.
The donor's wife has a rosary of large gray filigree or what I'd call a birdseye pattern if it were woven, separated by BIG gold filigree decade beads. At the bottom is a simple Latin cross, with 4 pearls in the joints.
The donor's daughter has a black bead rosary w/ a medallion at the end, and large faceted gold beads for decades.
On both, the pendant appears to be in the middle of a decade, with 5 'normal' beads on either side, which I thought was a bit unusual.
In the Museum of Fine Arts in Ghent:
Anonymous Master, c. 1480-1490, S. Netherlands
Holy Trinity with Donors and Saints , inv. no. 1973-AE
The wife(?) of a donor has a rosary w/ the cross visible. You can see 6 beads between decade beads. Oddly, the cross is not centred between decades, but is next to one of them. There's also 1 additional pendant that looks like a rock w/in a gold base. You can see two other 'rounds' on one side of the rosary, suggestiong 6-7 rounds total for the whole piece.
One non-rosary related observation: a crown perched on top of a travelling hat.
Master of the Prelate Mur, c. 1450
Adoration of the Magi , inv. no. 1903-E
The magi have arrived to worship Christ, and one of the leading travellers has flung down his hat in his haste to get to his knees.
His hat is shaped a bit like a Robin Hood hat, but the crown is rounder, more cylindrical, and has a pointy nipple on top. And within the brim of the hat, you can see his crown.
I mention this because SCA royals and royal peers tend to wear crowns and coronets on top of other headwear, regardless of period practice. I particularly dislike the wearing of coronets on top of straw sunhats, as I think it's looks very silly.
Judging from portraits and illuminations, kings and queens did not always wear their crowns. But the SCA convention is that anyone entitled to a coronet will wear it, particularly if they're on the throne.
This is the first example I've found of a crown within anything other than a cap of maintenance-style head covering.
I don't know if this is a good example: the Magi are not typical folk, they're decidedly exotic, and obviously Not From Around Here. This may be an example of their Strange Foreign Ways - so outlandish, that they wear crowns over their hats. Or maybe it's to help identify them - like a big arrow indicating that these guys aren't just wise, they're royalty too.
But I thought it was nifty to see anyway.