Blingbling did not come from a dictionary, but first appeared in a song "Cash Millionaire" written by hip-hop artists in the last century.
Blingbling, originally used as onomatopoeia, later became a popular term. A lot of jewelry will make a blingbling sound when worn together, so blingbling stands for dazzling, shining, dazzling and exaggerated jewelry here.
In the latest edition of Oxford Dictionary, the standard interpretation of "Bling" is: wearing brand-name clothes and bright jewelry.