A prince's wand is a piece of body jewelry meant to be worn in a trans-urethral penis piercing (prince albert, reverse prince albert, apadravya, ampallang, or dolphin). A prince's wand is a rod (usually surgical grade steel, but could be titanium or nylon; usually two to six inches long, but could be any size) with a bead at one end and tapered at the other, and with a small perpendicular stud sticking out near the beaded end. The bead at the end of the long bar sticks out the opening of the urethra, and the stud sticks through the trans-urethral piercing — the shape is somewhat like a police nightstick. Prince's wands can be hollow (to allow the passage of fluid) or solid, and are often used just for play but can be worn all the time — the added weight is said to make walking a pleasurable experience.
Though the simplest wand will be just a rod with a small perpendicular stud near the ball end, there are many variations possible on this theme. Rings on the front ball (bondage or slave ring) or stud ball (frenum ring), extra beads or spikes on either ball, extensions for the rod, ribbed or textured rods, hoses/nozzles/mouthpieces, sheathes, curved rods and even flexible plastic rods are all available. While most wands have one stud to fit in the piercing, custom jobs for apadravyas, palangs or dolphins featuring two or more studs are certainly possible. I've even seen one wand maker with a model that doesn't require a piercing: the pinless wand has a ring that circles around and behind the glans of the penis and keeps the wand in place. Prince's wands are also easily turned into chastity devices: in one model the ball at the end of the wand has a stud parallel to the piercing stud, and both studs have a hole drilled through them so they can be locked together.
If you're planning on wearing a prince's wand, the first thing to do is take some measurements: prince's wands are commonly custom made (and thus expensive, usually somewhere above $100 for a good one). The gauge of the piercing, ideal thickness of the rod, ideal overall length of the rod, ideal length of the rod before taper, and how far back the piercing is located are all important numbers to know before buying one or having one made.
References:
Steelwerks: http://www.steelwerks.ca/
BMEzine: http://www.bmezine.com/
John the Wand Man: http://www.princeswand.com/