Does any native know how to check if "Shankha Pola" Bangles I brought are original or fake? (read caption)

I brought these for 150 a pair from Konark, also brought a few more similar pairs from Jagannath Puri. But now my mum tells me that they could be fake, I did see with flashlight, can't find any metal rod but still confused, do anyone know any way to test the originality? (So that I can assure my mum 😅) Does any native know how to check if "Shankha Pola" Bangles I brought are original or fake? https://preview.redd.it/kze731qcc87e1.jpg?width=8160&format=pjpg&auto=webp&s=cdf300a747b6726388b334ca0f106bf83f86b141