Assertion: asterism | /r/CreatedBy | the difference
Facets:
Source sentences:
text: The star-effect or "asterism" is caused by the difference in refractive index between the host material and that of the dense inclusions of tiny fibers of rutile (also known as "silk"), the rutile having a greater R.I. causes the relative bright relief of a star in a host material such as corrundum which has a refractive index between 1.760 - 1.778 much lower than that of rutile.