Question

why does a diamond shine mpre than a glass piece cut to the same shape?​

Answer 1

Answer:

because the number of internal reflection of light happening in diamond is much more than any other glass piece

Answer 2

Answer:

Diamond shine more than glass piece of the same shape.It is due to the refractive index of both the medium that is R.I of diamond is more than that of glass . Hence critical angle of glass is more than that of diamond causing more total internal reflection in diamond/making it shine.