Milky CZ is another form of cubic zirconia, altered to make its form look milky. It comes in various colors, and can be cut into any shape.
Spinel is the magnesium aluminum member of the larger spinel group of minerals. Its hardness is 8, its specific gravity is 3.5–4.1, and it is transparent to opaque with a vitreous to dull luster. It may be colorless, but is usually various shades of red, blue, green, yellow, brown, or black.