They are fragile and need specific expertise to ensure that they are polished and cut to perfection. Any little flaw will show … we all know how black cars show imperfections more easily than white ones. Same concept.
This little write up sums it up:
https://www.girard-perregaux.com/jp_en/blog/the-story-of-onyx.html
Sometimes we forget that beyond marketing and holy trinity hype, that otter top tier brands will share suppliers and even expertise. The informal collaboration at a technical and artisanal level exists in a healthy collegiate type environment in the various Swiss enclaves.
🤝