Blue Spruce: Just as trees have growth rings; Blue Spruce will develop regular steely blue striations on the surface of the glass. Reduction develops these striations or rings. If kept oxidized, Blue Spruce will remain pure and offers a fully saturated blue-green opaque for stringers and blown work. Try reducing, then casing with clear glass for a neat effect! Amber/Purples look great with Blue Spruce as well. This color is a must have in any palette.