Gemstones and Mineralogy

[Alex Popescu]

are there any meditations where i could use gemstones ? like Lapis Lazuli and Onyx and many other gemstones ? i guess you match their atributes by colour , mineral substances from wich they are made  the way the ancients used them and all of that  ?i did not saw any link on JoS about gemstones , or if it is then i missed it