The Rogue and the Hellion by Connie Mason, Paperback published by Leisure Books, June 2002. The Rogue Trilogy, Book 1.
STAND ...

When an audacious highwayman holds up his coach and points a pistol at a rather crucial part of his anatomy, the Marquis of Bathurst has a critical choice to make --- give up his dead brother's ring or lose the family jewels. Gabriel decides to part with the memento, but only temporarily. He would track down the thief with the unforgettable green eyes if it was the last thing he did.

AND DELIVER ...

Everyone knew of the scandalous reputation of the Rogues of London. So when their most infamous member took her in his arms at a society ball, Olivia Fairfax realized his intentions were far from honorable.

Gabriel's hot pursuit made her emerald eyes widen and her pulse race, but was he after a lover or the hellion who'd dared to rob him at gunpoint?

Either way, Olivia knew it was now her turn to hand over the goods and she was more than willing to give him her body and her heart.