The Resin Rose is a precious ornament given to Yuki Kuran by Kaname Kuran in 30th Night. It is a miniature rose that blooms only once every ten years even in the depth of winter. Kaname had it hardened in resin to preserve it. It is fairly small, easily held in one hand, it is approximately 10 cm in height and 3 cm wide.
Kaname gifts the rose to Yuki on return from his long holiday, Yuki does not realise the significance until several chapters later, following her awakening and her memories return, she remembers Kaname promising a young Yuki, that he would bring back the rose for her to see as she was locked in the Kuran mansion and unable to see the field of flowers for herself.
The Resin Rose is the only significant item that Yuki takes with her in 47th Night upon leaving Cross Academy with Kaname. During 41st Night, Yuki suffers an outburst of power and causes a crack in the glass container. Later, when she talks to her young vampire self, she reaches out and finds herself grasping the Resin Rose.