Tsavorite has a deep green color caused by vanadium. Unlike chromium, this is helpful for a soft green color that would be particularly evident on large stones.
Unfortunately, “big” tsavorites are just as well known in jewelry sizes in good quality, a size of 5 carats is a rarity and very popular.
The most famous occurrence of tsavorite is in Kenya in the Taita Hills. Graphite slate is mined there, an actually cheap raw material and near the Lualenyi Ranch near the city of Voi.