Gemvara is a ring for Grace, also known as Mistress Red in Carte Blanche and its sequels. The gold ring is shaped in the form of a feather, accented with a red garnet.
Ray, Grace's vampire submissive, finds the ring in a pawn shop one night when his Mistress is working and he's out on his own. He knows as soon as he sees it that he has to get it for Grace: the garnet is just the color of her hair, deep and gleaming in the right light, and the shape of a feather reminds him of a play session, gentler than their usual ones but just as intense, during which Grace blindfolded him and teased him for hours with nothing more than a feather and her words. By the end, he was begging for release and ready to give his safeword, something he hadn't done in a long time.
The ring, however, is well beyond his limited means. Asking Grace for money is bad enough when it's to pay for the blood he needs to subsist, it'd be unconceivable to ask her to pay for her own present. He talks to the pawn shop owner, offering to work for the ring, but the owner is not interested. The only possessions worth something Ray owns are his art supplies, and as much as it pains him to even imagine his life without them, he asks the pawn shop owner if he would take them for trade. Again the answer is no, but the man asks Ray how good he is at making art. Sensing this could be his chance, Ray scribbles a quick portrait of the man on the back of an enveloppe to show his skills. The owner is impressed, and they strike a deal: Ray will create a large, lifelike portrait of the man's wife and new baby, and in exchange he'll get the ring.
Ray works on the portrait for more than a week - all he has are a couple of reference pictures and he wants it to be perfect. Grace asks him who the people are but he's evasive and only says they're 'friends'. When he gets the ring, he first thinks he'll present it to her for her coming birthday, but two months seem like a much too long time to wait, and he ends up giving it to her the same night he gets it. All he needs is a look at her beaming smile when she first sees it and he knows she remembers that feather as vividly as he does.