Due to the nature of the Duke and Duchess of Cambridge's current roles, still maintaining private lives and military careers, and only carrying out a few select royal engagements. HRH simply hasn't yet attended any tiara events.
Beyond the few evening functions she has attended, and daytime engagements, we haven't yet been afforded the opportunity to see the extent of HRHs jewellery collection, nor her taste in jewels and "glitter".