Ernie Ball Music Man model played by Eddie Van Halen during a spontaneous Black Sabbath studio session hits the auction block

An Ernie Ball Music Man electric guitar, which was once borrowed by Eddie Van Halen for an impromptu studio session with Black Sabbath, has gone up for auction.

At Guitar World, we see our fair share of guitar auctions – we’ve even collated a list of the 10 most expensive guitars sold at auction – but this one particularly stands out, owing to its remarkable backstory.

Back in 1994 – a year when Sabbath were working on their 17th album Cross Purposes and Van Halen were on tour – guitar greats Eddie Van Halen and Tony Iommi both happened to be in Birmingham, England at the same time on April 28.

In order to capitalize on the coincidence, Iommi invited Van Halen to a rehearsal session at the studio where Sabbath were working, and suggested they swing by a local guitar shop, Musical Exchanges, to get Eddie a guitar for the occasion.

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As Iommi once recalled in an interview with Rolling Stone, “I said [to Eddie], ‘I'll pick you up from the hotel. Let's go and get a guitar.’ We went down to the music shop in Birmingham. I said, ‘Can you lend us a guitar for Eddie?’ So Eddie came in with me, and we got one of his guitars, his own model. And he came to rehearsal.”

Of course, the employees of Musical Exchanges weren’t going to say no when Van Halen and Iommi came knocking asking to borrow a guitar.

Opting for a Translucent Pink-finished iteration of his own signature guitar, Van Halen then joined Iommi and Sabbath in the studio, and ended up helping write Evil Eye.

“We played some of the Sabbath stuff for him,” Iommi continued. “One of his favorites was Into the Void, strangely enough. We played that and we went back to writing. I think it was Evil Eye, and I said, ‘Go on, you play the solo on this.’ He did and it was really great. When we recorded it, of course, I tried to duplicate that, but I couldn't.”

Though Van Halen’s take didn’t make it onto the final mix, Iommi confirmed he still owns the tape of Eddie’s effort, saying, “I don't know where it is amongst my lot, but there is one. I know I've got one. It was a real gem.”

At the end of the session, the guitar was duly returned to Music Exchanges, where the staff quickly cataloged the instrument, owing to the fact its value had quite clearly skyrocketed.

As for specs, the six-string – serial number 80351 – sports a figured maple top and basswood body, as well as a pair of DiMarzio humbuckers controlled via a three-way selector switch and master volume knob.

Other appointments include a maple neck and fretboard, Floyd Rose tremolo and Schaller tuners.

Accompanying the axe is a photocopy of the 1993-94 Guitar Buyer's Guide, in which Van Halen discusses the event.

The auction for the Ernie Ball Music Man, which is expected to sell for between $8,800 and $11,400, ends tomorrow (April 4) at 7am ET.

For more information, head over to Bonhams.