to verify it is tsavorite garnet
Did the jeweler purchase the gem or cut it from rough? Is the gem certified from a reputable laboratory AGL, GIA, GRS? Can you get a refractive index on the gem to verify it is tsavorite garnet? It looks like the table of the gem is either dirty or scratched. Color is very saturated and it looks to me like chrome diopside or dark green tourmaline. Tsavorite can be expensive so better to make sure it is the real deal before spending lots of $$$$
Youtube video here ... Asking price for this stone is about $2K.