In Real Life
The "star" pattern that this mineral is known for is caused by rutile (Titanium dioxide: TiO2) crystals that have impregnated the host corundum crystal. Star rubies are only smoothed into cabochons, as cutting them with facets does not allow the star pattern to be seen.
[INORGANIC:RUBY_STAR] [USE_MATERIAL_TEMPLATE:STONE_TEMPLATE] [TILE:15][IS_GEM:star ruby:star rubies:OVERWRITE_SOLID][DISPLAY_COLOR:4:7:1][MATERIAL_VALUE:60] [ENVIRONMENT_SPEC:RUBY:CLUSTER_ONE:1] [SOLID_DENSITY:4005] Common to corundums. Range 3960 - 4050 [STATE_COLOR:ALL_SOLID:RED]