I have been a lapidary and silversmith for over 50 years. This started while getting my degree in geology at the University of Wisconsin Madison. I enjoyed field trips to Wyoming and continued a lifetime of rock collecting. My parents also joined in the pursuit of collectible rocks, especially jade.
I use Wyoming nephrite jade for my knife blades. The jade I use is from a family collection which was collected and purchased 50 year ago. These jades are not commonly on the market today and include apple green and ghost jade (jade which includes shadows of quartz crystal that have been replaced by jade(i.e. pseudomorph).
Nephrite jade has been used for weapons and tools before the bronze age because it is the toughest natural stone. Because it can't be chipped as in the case of flint, each piece had to be ground using other stones. This was time consuming and labor intensive. The tools could be handed down for generations. After the bronze age, jade was still used for ornamentation and ceremonial purposes and as status and rank symbol.
I use other natural stones, bronze and silver in some of my knife handles. There will never be duplicates. Each knife is individual and signed by me. I cut the rocks into slices in an oil bath diamond saw. Pieces are selected, cut and ground into desired shape using diamond tools. Then assembled using various industrial epoxies. The whole piece then gets a final grinding and polishing with diamond tools. Start to finish requires several weeks.