I'm surprised that there is enough difference between borosilicate glass and soda lime glass refractive index. They are also both slightly mis-matched to minera

I'm surprised that there is enough difference between borosilicate glass and soda lime glass refractive index. They are also both slightly mis-matched to mineral oil but I guess good enough for a visual check. Appears its not consistently reliable. Also, its refractive index not refractory.