This was from the Yemeni times long ago...
Qualities of Jambia in Yemen
The most famous sort of the Jambia is that which has a “saifani” handle. It has a dim yellowish luster. When it is clearer, it turns into a yellow color. This is called saifani heart.
Some of the saifani handles are called “Asadi”, when they turn into greenish yellow. When the handle becomes Whitish yellow, it is called Zaraf. There is also Albasali (onionish) kind whose color looks like white onion.
Lots of other on the spot information in the Pachyderm magazines & articles, including many interveiws with jambiya makers,sellers & the dealers & smuglers of rhino horn.