You Want My Ring？Get on Your Knees.

GoodShort synopsis

I'm Isa Borgia, the daughter of the most powerful Don in Corvina. My father worries I'll marry the wrong man on a whim, so he arranges for me to be engaged to Luca, the rising heir of the Marino family. It's an arranged marriage, but that doesn't mean I've lost all my say. The very least I can do is choose a ring I genuinely like. So, I go to the mafia auction. When the diamond ring appears as the final jewel of the night, I lift my paddle. Just before the gavel falls, an arrogant voice comes from behind me. "A country bumpkin like you thinks you can compete with me? Do yourself a favor and leave." The auction hall goes quiet for a few seconds. The only sound comes from the camera shutters clicking around the hall. I turn and see a woman in a gold couture gown. Her mouth curves in a casual smile, as if she owns the place. Before I can say a word, the auctioneer rushes to close the bid.
"Sold! Congratulations to Ms. Sofia Lopez for winning the final lot, the Eternal Star!" My brows pull tight, and a hot spike of anger rises in my chest. "You ended the bidding early! Do you even follow the rules here?" Sofia turns around and gives me a once-over, her gaze sharp as a blade. 
"Rules?" She lets out a cold laugh. "Come on. I'm Luca Marino's favorite godsister. Around here, I make the rules!" I can't help but laugh. What a coincidence. So, she's my fiance's godsister. I pull out my phone and call him. "Luca, your godsister just snatched the engagement ring I picked out. How are you going to handle this?"