Size will play major part in how you choose your necklace pieces, because
you don't want the piece to be too big. Average sizes will be about the size of a quarter or half-dollar. Some larger
pieces can be used if they are a certain shape, like the one I am wearing now: it's about 2 inches long at its base and it
narrows as it nears the top.
Make sure your pieces are thin, too. 1/4 of an inch is the optimal thickness. They can
be thinner, but not much thicker.
Drilling the holes...The hole shouldn't be more than 4.5mm (about the size
of a copper BB) in diameter. The bridge--the small isthmus around the top of the hole that the leather hangs on to--can
safely be about 1/8 of an inch thick.
You can drill 2 holes side-by-side too: here the bridge can be about 1/4 of an inch thick
but the space between the 2 holes shouldn't be more than 1/8". This is harder to do, so to see it isn't a normal sight.
Adding the jade: bend and crease the leather strap in half, then
insert the crease through the hole in the jade. Open the loop and slide the rest of the leather through and tighten.
Each strap should be about 20-24 inches long.
Tying it off: I prefer to use cheap screw clasps like those
found on surfer shell necklaces, but you can take each strand and tie a pretzel knot around the opposite strand, creating
a kind of slip knot that can be loosened or tightened.