Hóa ch?t s?n xu?t, kinh doanh có ?i?u ki?n trong l?nh v?c công nghi?p ???c pháp lu?t quy ??nh ra sao?Nearly all tanzanite is heated at reduced temperatures to remove brown undertones and give a more appealing blue / purple color.[45] A considerable portion of all sapphire and ruby is addressed with a number of heat therapies to boost both of th