The lovely azurite malachite & chrysocolla gemstone cabochon shown here is 19mm long.  It is available to be handcrafted into a custom made ring or pendant for you.

These three stones are closely related. Dark blue azurite and light to dark green malachite are basically copper carbonate, having the same chemical composition except for one oxygen molecule. Azurite, when in the earth, can slowly change to malachite, so it is rare to find azurite without malachite being present. Chrysocolla, a light green/sky blue stone, is a copper silicate and often occurring in the same stone with them. Turquoise, a copper aluminum phosphate, is a cousin to these three and can frequently be found in the same copper deposit locations.