I’m in search of a single young adult novel in which the main character is a young woman, she’s been training in an academy of girls, learning how to fight (and possibly use magic?) She comes of age and there is a ceremony where her eyes are replaced with gemstones, I believe they were obsidian but amber or garnet are also sticking out in my mind. She goes on a journey where she meets a man (and later there is a romance between them). They are on a boat at one point, she senses a monster or wizard and uses magic to defeat them. At the end of the book she uses the power of her gemstone eyes to speak to a council of people about something important, then can’t turn off the power and it slowly drives her mad. A former witch (sorceress?) finds her and manages to remove the stones and gives her blue eyes. I think one of the names starts with an s, could be wrong. I read this around 2015, the cover was, I believe, a young woman with gemstone eyes. Perhaps a golden background. Any and all help is greatly appreciated!!
This might be Hawkspar (2008) by Holly Lisle.
The summary on Goodreads describes how the slaves of the order can be chosen to receive magical eyes of stone, and the protagonist gains the power to see through time.
A sample chapter on the author's site introduces us to a convent-like setting whose female "penitents" are taught martial arts and other skills, and to the magically-endowed leaders who are called "Obsidians."