Green haüyne, also known as hauynite, is a rare and valuable gemstone that can be described as follows:

• Color: Green haüyne can range from yellowish green to blueish green, with blueish green being the most common. The color is influenced by trace elements in the crystal structure.

• Clarity: Clean green haüyne gems are rare, and most are slightly "silky" in appearance.

• Size: Most green haüyne stones are under 0.40 carats, with 0.10-0.25 carats being the most common size.

• Fluorescence: When exposed to longwave UV illumination, green haüyne displays a bright orange-yellow fluorescence.

• Refractive index: Green haüyne has an average refractive index of 1.50.

• Hydrostatic specific gravity: Green haüyne has a hydrostatic specific gravity of 2.41