What color is chrome? Chrome is a designation for a green form of a species of tourmaline called Dravite. It can't not be colorless by definition and therefore bi-colors with chrome can not exist by definition. Colorless and green bi-colors can exist in other species of tourmaline, but they are not the most desirable.
Sodium, magnesium and potassium do not color tourmaline. The three elements along with calcium, which should be included in the group, form a species of tourmaline that is colorless when pure. The chromophores in tourmaline are, iron, titanium, manganeses, copper, vanadium, chrome and color centers.
All rings with fine gemstones should be removed before heavy work. Tourmaline varies in its toughness, but does not take exceptional care in its uses in jewelry. Toughness is a separate issuer from hardness.