Gem is a "nice to have" but isnt needed. I usually use 1 sp2 and then sp1 spam for the rest of the fight. If I only take blocked hits I usually end the fight at 100% health (it is very recommended that you run willpower with him). Sometimes I may stack 2 auras from the sp2 but you have to be way more aggressive to get back into ur sp1 cycle.
What Science champs do you already have awakened? He's worth a gem but not over someone like Void or CAIW.