The artful and precise faceting of a ruby determines how the light responds to it. Ultimately this is what determines how much sparkle or life the ruby has. The gemstone cutter should facet the gemstone in a way that the maximum amount of light is entering the gemstone and reflecting back out. If the culet, or bottom facet, is cut too large, the light will leak out of the bottom of the ruby. The angles of the facets determine how the light reflects within it. If the faceting is not symmetrical, the sparkle can be affected. Ruby cutters must precisely fashion a ruby to allow the most brilliance and fire to come through.