Here's why:
* Tanzanite quartz is a misnomer. Tanzanite is a gemstone itself, a variety of zoisite, and it's not related to quartz.
* Quartz is a different mineral entirely. It comes in many varieties, like amethyst, citrine, and rose quartz.
* Diamonds are a completely different mineral made of pure carbon. They are known for their extreme hardness and brilliance.
While all three are gemstones, they are distinct minerals with different chemical compositions, properties, and appearances.