There's a field of academic study that sits at the intersection of geology and fashion, and that's gemology: the study of gemstones. Identifying, categorising and grading gemstones is a specific skillset, but valuation can be more subjective, particularly when it comes to regional variances such as with the inordinate popularity of jade in China.

Christina Chao is a gemologist and jewellery designer in Shanghai, who is passionate about translating the science of gems into the art of jewels. And as she describes in today's episode, that's a skill she often puts into practice when advising nervous men looking for engagement rings for their girlfriends. Or indeed nervous podcasters who don't know the first thing about gemstones.