Most geode crystals are not of gem quality, being off-white to dirty grey in color and opaque with little sparkle. Therefore, druzy quartz crystals are typically treated in some manner.
Irradiation and heat treatments can be used on clear quartz to create color. However, not all clear quartz will accept those treatments to create color in the gemstone. Do not be concerned about irradiation treatments used on gemstones. If you own a colored diamond, it was most likely irradiated. For the safety of public health, the NRC (U. S, Nuclear Regulatory Commission) regulates the distribution of irradiated gemstones. Several months after the gemstone treatment, any measurable radiation had decayed and the gemstone is safe to use and wear.
Chemical vapor deposition is a treatment where precious metals (gold, silver, titanium, and platinum) coat the surface of the crystals. Sometimes the cut pieces are dyed before treatment, sometimes not. Titanium can be used to coat druzy crystals, creating a bright metallic finish. (Private collection, Judy Larson)
Many of the druzy quartz gemstones we use in our jewelry are dyed in some manner.
(Private collection, Judy Larson, purchased from wirejewelry.com)