Hairdressers/Hair Stylists/Hair Crazy

GG
So, I am currently a highschool girl in Cosmetology training (first year student) and I am looking for a new hair color to do (still have virgin hair) . I have a square shaped face (sadly) with a natural medium/dark brown hair color, about level 4-6 with jet black eyebrows as well. 
my goal in hair color is to get a black hair color that also shines with a purple tint. any color brands you guys recommend? Again, I have virgin hair so I would like to know somethin that works best.