Niobium is stunning. Niobium is an element on the periodic table. It's called a reactive metal as you can change its color with heat and electricity. It's the most difficult metal we saw cut, and we colour all our rings in house. Colouring can vary from batch to batch so it's important that you order all the rings you need for one project at the same time. The oxidized layer of colour is only one layer thick... the piece of metal doesn't colour solidly... only the surface coating. So you may see the colour fade over time and wear. How you treat your jewellery will really make a difference in the length of time the colour will hold up. We recommend that you don't wear Niobium in the shower, pool or bath tub. Do not clean it in toxic jewellery cleaners or tumblers, as this will wear at the colour coating. Some people have very acidic body chemistry and may wear the colour off faster than others. It is also hypoallergenic so completely safe for people with metal sensitivities and allergies!