{blackbabes} Jay-Z & Beyonce -- Scoping Ricky Martin's $12 Mil Mansion

Jay-Z and Beyonce went mansion-hunting last week in Miami Beach -- and one of the SUPER-EXPENSIVE homes they checked out belongs to one Señor Ricardo Martin ... TMZ has learned.

We confirmed with the realtor that J&B took a walk-through the 9,491 square-foot ocean-front pad last week -- but it's unclear if the couple is interested in making an offer.

According to official records, Ricky's trying to score a hefty profit on the estate -- because he bought it in 2005 for $10,000,000 .. and now he's listed the house at $12.5 mil.

The place is pretty sick -- boasting 7 beds, 10 baths, a swimming pool ... and it's located in one of the ritziest parts of Miami Beach, close to Miami Heat superstars Dwyane Wade and Chris Bosh.

As for Ricky, neighbors tell us he was a great neighbor -- and they're sad to see him leave.