It's actually a "tenner", a string of ten large beads. There is a ring at one end, a cross, the usual ten beads, and then an eleventh, larger bead which is a "prayer nut," carved on the outside and opening to show more carving on the inside.
Actually, the whole thing is an amazing, minutely and intricately carved work in boxwood -- a wood often used for such virtuoso exhibitions of carving, since it's very hard and close-grained. To quote the catalog:
"The Cross is carved with the Crucifixion and the Four Evangelists on one side and the four Latin fathers on the other. The Ave beads are each divided into five roundels, and carved with figures of ten of the the Apostles, with the Sentences of the Creed, the Prophets and Sibyls with appropriate texts, and scenes from the Old and New Testaments. The Pater bead [5.4cm diameter] has three rows of eight roundels with further scenes, including the royal arms of England and the letters 'he 8' (for King Henry VIII) and 'k.a.' (for Queen Catherine of Aragon), and the two remaining Apostles; it is hinged and has another two scenes inside of the Mass of Saint Gregory and the Virgin and Child Adored by Angels."
The entire string is 58cm (almost 23 inches) long. It was bought by the sixth Duke of Devonshire (1790-1858) for 200 pounds, from Rundell and Bridge (the Court jewelers), after being in the keeping of the Jesuits at Paris for many years, and then in a private collection.
I've been looking for a good photo of this for quite a while, since the only ones I've been able to find are small black and white versions, and usually they're from books printed before about 1990, when there seems to have been something of a revolution in photography and color printing that allows more recent books to have bigger, sharper and clearer close-up photos than ever before. (People with over-40 eyes appreciate this a lot.)
This photo is in The Devonshire Inheritance: Five Centuries of Collecting at Chatsworth [Ed. Frances Kianka; Art Services International, 2003, ISBN 0-88397-138-0], printed to accompany a traveling exhibit that's been making the rounds in the U.S. (I think it's currently in Palm Beach, Florida). There's a half-page photo of the whole thing, and a closeup of two of the beads.
That's the good news [grin].
The bad news? The fact that this is, indeed, part of that traveling exhibit means that I did -- as I thought -- miss seeing the thing in person by one (1) day. I was visiting my parents in Boston early in November, and the day that I arrived was the day after the last day of the exhibit at the Peabody Essex Museum in Salem, Massachusetts, not that far away.
Oh, well :)