$(i)$ Blue cupric metaborate is reduced to colourless cuprous metaborate in a luminous flame

$\begin{array}{*{20}{c}} {2Cu{{\left( {B{O_2}} \right)}_2} + 2NaB{O_2} + C} \\ {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \downarrow \,{\text{Luminous flame}}} \\ {2CuB{O_2} + N{a_2}{B_4}{O_7} + CO} \end{array}$

$(ii)$ Cupric metaborate is obtained by heating boric anhydride and copper sulphate in a non luminous flame.