No, this isn't a Dr. Seuss book :)

After working with guitar strings for 6 years (!!!) I have learned a thing or two about them.

1. Guitar strings are SHARP.  The rule of the studio is NO BARE FEET.  They are like tiny razor blades.  Anyone who has changed guitar strings can tell you their tales of woe.
2. Guitar strings try to ATTACK PEOPLE.  Okay, so this goes along with them being sharp, but really they spring back at you as you attempt to coil them.  Proceed with caution and use protective eyewear!
3. Guitar strings age differently.  Different strings are made of different metals and different wrapping processes.  This means that they will wear and age differently over time.  This is why we recommend never getting your bracelet wet, or exposing it to lotions/perfumes.  Because the strings are donated, we never know quite how they will react to various products.
4. Guitar strings smell funny. Seriously, there is nothing we love better then the metallic stink of a box of freshly donated strings.
5. Guitar strings take patience.  Seriously, have you ever had a big knot of cords?  That's our life here at WYM.  And we LOVE it!

While these tidbits have more to do about the usability of strings as jewelry, here is a great piece about how string differences affect sound.