In Grave Peril, the silver ring is described as "a plain silver ring, its interior surface inscribed with a number of runes", worn on the right hand. By Small Favor, Harry has upgraded -- "there was one of them on each finger, a band made of three rings woven into a braid."
Small Favor describes the blasting rod as "a simple wooden rod, a couple of feet long, heavily carved with sigils and runes".
The staff is described as "heavy", "carved wood" and a "solid length of oak". It's quite long, judging by this:
Luccio sat beside Gard with her slender staff and her silver rapier resting on the floorboards between her feet, though my own staff was a lot longer and had to slant back between the front seats and past Gard’s head, up into the rear window well.
It's possibly also carved with runes--
his right hand he carried a wooden staff carved with runes that looked almost precisely like my own
-- and, although Storm Front refers to it as "pale, smooth wood", Blood Rites says "I focused it on my staff, and the sigils and runes carved along its surface became suddenly suffused with eye-searing scarlet light."
In Grave Peril, both wand and blasting rod are described as "freshly carved and still a little green around the edges".
ETA: as per Joakim Elofsson's comment, Ghost Story has the staff as "six feet of oak" with "[r]unes and sigils carved in a tight spiral down the length".
In Storm Front, the shield bracelet is described as a "bracelet of tiny
medieval-style shields" and "bracelet of silver shields"; that one is destroyed and replaced. In Death Masks it's "a silver bracelet dangling a dozen tiny, medieval-style shields" but Small Favor describes the redesigned bracelet as "made of a braid of many metals, the chain of the bracelet was hung with multiple charms in the shape of medieval shields."
Bob's skull is described in Storm Front as a "bleached white human skull." It's "a few hundred years" old. When Bob is talking, "a pair of lights came up in the empty sockets of the skull, orangish, flickering like candle flames." It has a bottom jaw - "his bony teeth rattled when his mouth clicked closed again."