I often have people ask me what they can do with birthstones that aren’t very complementary or that need “something” to tie them together. My answer is usually either 1) skip the birthstones if you aren’t sure or 2) add a stone that ties in both colours but that is representative of something and not just a random addition.
The above piece is a perfect example of option 2: it features amethyst for February and citrine for November. To tie the look together, I found a Tiffany stone that had shades of both colours. Furthermore, Tiffany stone represents love which is the most important part of creating this pendant for the two parties it represents.