In borax bead test which compound is formed?

Solution :
In borax bead test the coloured $$meta$$  borates are formed by transition metal salts.
\[N{{a}_{2}}{{B}_{4}}{{O}_{7}}.10{{H}_{2}}O\xrightarrow[-10{{H}_{2}}O]{\Delta }\]     \[N{{a}_{2}}{{B}_{4}}{{O}_{7}}\xrightarrow{\Delta }2NaB{{O}_{2}}+{{B}_{2}}{{O}_{3}}\]

\[{{B}_{2}}{{O}_{3}}+CuO\to \underset{\begin{smallmatrix} \text{Cupric}\,\,\text{metaborate} \\ \left( \text{Blue}\,\,\text{bead} \right) \end{smallmatrix}}{\mathop{Cu{{\left( B{{O}_{2}} \right)}_{2}}}}\,\]