Answer:
Impurities
Step-by-step explanation:
Impurities in the crystal lattices of minerals can lead to the different colours of quartz we know. Some are amethyst, rose quartz, e.t.c
When impurities occupy the crystal position of a mineral they reflect light in a different way compared to a perfect cut.
Different varieties of colour quartz have their own specific impurities causing the colour sensations we see.