The usual-ring sizing rules apply differently in this case due to the design and large dimensions of the Classic and Large Model Trinity rings. Cartier recommends that you select a size two sizes smaller than that indicated in the Cartier Ring Size Chart. For instance, should your usual size be 50, select a size 48 for these models.
The three bands of the Trinity ring are assembled in such a manner as to allow the ring to move easily and not catch. To reset the bands of your ring, roll the ring and set it down flat. Make sure the bands are positioned correctly, as shown in the two images below.