Quartz

Advantages:

• Silicon and oxygen are the two most common elements in earth's crust
• much lower than diamond but still decent hardness

Disadvantages:

• low crystal structure symmetry
• questionable passivatability
• much lower than diamond but still decent hardness

Color based names

• 🟨 citrine https://en.wikipedia.org/wiki/Citrine_(colour)
• 🟪 amethyst https://en.wikipedia.org/wiki/Amethyst
• ⬛ smoky quartz https://en.wikipedia.org/wiki/Smoky_quartz

Related

• Silicon, Oxygen

Stishovite a polymorph of SiO₂ other than quartz that is:

• much harder
• much denser
• has higher crsytal structure symmetry (the same as rutile)
• is metastable (hopefully)

There are several other known polymorphs of silicon dioxide.
One of them is Seifertite which is also a denser and harder thah quartz.