Mickey Mantle Gem Mint 10 Signature on an OAL Bobby Brown Baseball. Lot 403. Mickey Mantle Gem Mint 10 Signature on an OAL Bobby Brown Baseball. Mantle signed the sweet spot. The ball has strong pre-printed areas and shows somewhat uneven off-white to cream-colored toning. Authenticated by Kevin Keating. Winning Bid $324. Back to List Winning Bid $324 Back to List