I'm curious to know how their algorithm works when a site offers truly unique items? In other words, if I was buying a custom hand-crafted ring what would it re

I'm curious to know how their algorithm works when a site offers truly unique items? In other words, if I was buying a custom hand-crafted ring what would it recommend? Going a step further, if I was buying the Mona Lisa, would it know to recommend me other Da Vinci items, or other renaissance items, or would it fail to make that inference due to there being no co-occurrences in purchasing behaviour.