I bought some quite a few years ago, and also was disappointed in the range of color. My understanding is that they don't let the good blues out of the country, and haven't since shortly after the blue was rediscovered. The brown rind is from weathering and is usual in jadeite (though the rind flakes off and is often not present in stream-tumbled cobbles). AFAIK heat treatment isn't used to improve jadeite's color or translucence (this is done by bleaching and acid baths and/or dye followed by resin treatment). The only people I know that have tried heat-only treatment reported that it either turns the stone shades of yellow-brown or red-orange, rather than improving anything. Supposedly, some have treated the Turkish purple to drive off some of the yellow-browns, but that seems counter-intuitive and no verification on that. Heating weakens the stone and doesn't produce the more desirable colors, so I wonder why anyone would do it unless it was very low grade stone to start with.