There are two common methods to acheive the grey color for cosmetics. 

Aluminum pigment is a popular choice as the grey metal pigments. The most famous products in the market is Eckart Visionaire series. However, aluminum pigments cannot be used in any cosmetic formulation containing water, which restricts its applications.

There are always some companies making grey pearl pigments by coating carbon black or black iron oxide. This technique can acheive the grey color but the gloss and metallic effects are diminished. 

TechnoGrey range offers a new option to acheive the grey effects with excellent gloss and metallic effect. TechnoGrey is made by Pritty patent technology. The composition is only synthetic mica and titanium dioxide without addition of any carbon black or grey colorants. It can imitate the metallic effects of aluminum pigments. In addition, it can be used in all formulations no matter it is oil based or water based.