"Perhaps, because Seal doesn't sing bad songs," the Kiss From A Rose singer responded.
The Lorde shade was a critique too far for some viewers:
When Stone performed a second song later in the show, Kruger asked Seal if she'd changed his mind after his 'strong' critique of her previous performance.
"It wasn't strong, it was just truthful. What's your question?" he shot back.
Seal also slammed a Kiwi contestant during the episode; Kelly Rowland's artist Hoseah Partsch, but Seal's fellow judges weren't having it.
Partsch had the entire studio audience singing along to a rendition of Whitney Houston's I Wanna Dance With Somebody - but Seal criticised him for "not connecting with the audience."
"Him moving the audience from left to right, and them singing every note, wasn't an interaction? He had a complete connection, I completely disagree," said Rowland.
"If that wasn't connectivity, then I'm living in a world gone insane," said Boy George.
Seal returned to The Voice this season after a three-year absence - and he's clearly proving to be the show's most, ahem, controversial coach:
