On November 22, 2016, Kate wore this pair of diamond earrings.
We know she borrowed them from the Queen, because HM wore them in 2012.
The main component of the earrings is a substantial pendant drop. The drop features a loop of small white diamonds formed into a teardrop shape. The center of the loop contains a linear formation of diamonds: three small bezels and one larger at the bottom. The pendant is affixed to a pear shaped stud. The stud features a single white diamond in a halo setting. Flanking the section between the pendant and stud are two marquise diamonds.
Here they are on Kate: