The pendant for this hemp necklace is a  tagua nut (vegetable palm ivory) pill box measuring: 4.8 x 3.5 x 2 cm. (1 7/8" x 1 3/8" x 3/4"), that I had hand-finished;  into which, I inlaid a 16 x 12 mm. onyx cabochon.  

The swivel lid closes tightly to keep your treasures safe.  

Its  inner chamber’s dimensions are approximately: 2.3 x 2 x 1.2 cm. (7/8" x 3/4" x 1/2").  
I  filled all cracks inside, due to germination, with tagua dust and  a non-toxic, acrylic furniture finish, that I then ground smooth.

For the neckpiece itself,  I did macrame with black and mahogany brown colored hemp;  using: carved, carnelian discs;  onyx rounds and faceted, twisted tubes;  bone skull beads; and buffalo horn rounds;  and a glass crow bead.   

The length is adjustable;  starting at 38 cm. (15"), up to 112 cm. (44").   
Just slip it over your head and slide the lock knot to desired length.

If you would like it shorter, you can specify the length desired at time of purchase (no less than 60 cm. or 24" so it will still fit over your head), and I can easily shorten it.  

The necklace also comes with a storage pouch for safe keeping. 

Tagua nuts are a renewable product of the rain forests of Central and South America. 
They are a viable alternative to animal ivory.   

The last picture shows a raw tagua nut, so, you have a better idea what I start with.
Each nut has its own unique pattern, similar to a fingerprint.