Conversation so far:
What is JEM for Steve Vai?
Vai designed the Ibanez JEM guitar
What was unique about the Ibanez JEM guitar designed by Steve Vai?
a unique instrument that incorporated a series of groundbreaking designs that have since become staples in feature throughout the guitar industry
What was different about the Ibanez JEM guitar's sound
Vai says, Stratocasters had whammy bars but limited. Les Pauls had humbuckers but no whammy bar. Neither guitar had twenty-four frets. So I had these elements implemented into a Superstrat.“
What was Steve Vai's connection with Universe Guitars
Another design by Vai was the Ibanez Universe, the first production seven-string guitar
Did Steve Vai design any more guitars
Vai had several custom prototypes of these guitars built by Joe Jem Despagni, a custom guitar luthier and friend of Vai's.
Are there any other interesting aspects about the Steve Vai article?
After the pre-production prototypes were perfected, the first production Ibanez JEM 777 guitars were unveiled at the NAMM Show in 1987.

Question: How popular was it
Self-contained rewrite: How popular was the Ibanez JEM 777?