It's in His Kiss by Julia Quinn

One of my co-workers told me about the Bridgerton series by Julia Quinn. The series is about the love lives of 8 siblings in 19th century London, all very popular and each with his or her little quirks. It's a clever, witty series with just enough romance thrown in without it being overwhelming.
It's in His Kiss is the 7th book in the series, focusing on Hyacinth Bridgerton, the youngest in the family. Hyacinth is 22 and in her 4th season. She has been proposed to 3 times her first season, twice her second season, and once the past season. So far, there are no takers for this season. Hyacinth is outspoken, opinionated, and loves a good battle of wits. She is not the type of young woman to allow a man to tell her what to do or to be coy and demure. Perhaps this has something to do with her husband-less state?
Lady Danbury (who makes an appearance in all of the Bridgerton novels, an opinionated old woman who wields a mean cane) has a grandson, Gareth. Gareth and his father do not get along at all and due to sad circumstances, Gareth becomes his father's heir. Until his father kicks it, however, Gareth is practically penniless. Lady Danbury dotes upon him though (and Gareth is very good to his grandmother) and would like to encourage her young friend Hyacinth to entertain the idea of perhaps becoming affectionate with Gareth.
Being a romance, these two main characters do get involved, but not entirely in the way one would think: it begins with an diary in Italian and the promise of hidden jewels. And a very poorly written romance novel.
Quinn's Bridgerton series are fantastically fast reads; the characters are engaging, the details good, and the plot entertaining with a dash of seriousness and a whole lot of humor.