By Jove
Definition 1 of 1
Pro Tip 1/3Expressing Awe
Used when something impresses you or exceeds your expectations. 
By Jove, that magician's act was astonishing!
Pro Tip 2/3Archaic Exclamation
It's an old phrase, so use it when you want to sound dramatic or humorous. 
By Jove, this antique vase is older than I thought!
Pro Tip 3/3British Flavor
The term is distinctly British, giving your speech an English touch. 
By Jove, this tea is simply splendid!