Scatter plot of Lada indices n(J–H) and n(K_S –W1) for the HBe stars studied in this work. The A_V was varied by 25% and 50%, and the resultant index values are marked with plus and diamond symbols, respectively. The symbols are marked in blue if the A_V was increased and in red if the A_V was decreased. The inset subplot explains the symbols and colours used in the plot with the respective A_V value above each symbol.