Rebel Heiress (The Diamonds) by Amalie Howard

Lady Rosalin Chen has a secret—she isn’t as vapid as she pretends to be. In fact, she’s a computing genius and smarter than most of her peers in the ton, including her own cousin, Ansel. It’s a secret she’s kept for years, not that hiding her intelligence has done her any favors in the marriage department.

In fact, after several dismal social seasons in London, she’s practically considered a spinster. With little to lose, she decides to set her sights on getting a proper education rather than finding a husband. Disguised as Ansel, who truly could be her twin, she attends Cambridge University while he galivants around Europe on a secret Grand Tour.

There Rosalin crosses quills with the Trinity College’s mathematics prodigy and her tutor Tarik St. Clair. For the first time in her life, Rosalin is genuinely intrigued by a boy. His mind seems to be as sharp as hers. Unfortunately, as a commoner, Tarik doesn’t fit her parents’ expectations. But what if he could? What if she concocted one more audacious plan that could raise his station and finally take her off the market? She just has to hope that her lies don’t catch up to her.