Unity Cosmetics products contain no nickel.
Nickel
Nickel is a mineral, obtained from limonite, granite and pendalite (three types of mineral, the last of which only occurs in magma that reaches the surface during volcanic eruptions). On the ingredients list, nickel is indicated as Ni. Nickel occurs widely in food and in stainless steel. Regularly wearing piercings, earrings and belts with metal buckles can cause a nickel allergy, which shows up as an itchy rash that may produce watery blisters. Someone with a nickel allergy is generally more likely to develop an allergy or skin irritation to many other ingredients, such as cobalt, copper, zinc, water, soapsuds and so on.
Nickel is hardly ever used in make-up. Unity Cosmetics make-up products contain no nickel.
Nickel is often confused with iron oxide. Iron oxide gives colour to a product and is used by almost all cosmetics brands (Unity Cosmetics too). Iron oxide (recognisable on the INCI list as CI 77499, 77491, 77492 and 77489) comes from a natural mineral called "haematite". When haematite is brought into contact with oxygen, iron oxide forms — frequently used as a pigment in cosmetics (and, incidentally, regularly found in food too). Iron oxide is a widely used and safety-cleared ingredient that, unlike nickel, rarely if ever causes someone to develop an allergy.
Iron oxide is used in most Unity Cosmetics products because it's a mineral that produces beautiful colours and generally doesn't cause negative skin reactions.