Rutile is a substance that makes frequent appearances in the gemstone world. Rutile is responsible for the "silk" that makes some rubies and sapphires especially valuable. Natural rutile is rarely found as a gemstone (it is mostly seen as inclusions in other gems) and is classified as a collector's stone.
Rutile is often cut as a curiosity,the gems are usually deep red in color, but the color is so intense that it cannot be easily seen in stones larger than 1 carat.
Cabochons of rutile might show reddish reflections in cracks and along imperfections. Swiss rutile seems a bit more transparent than material from other localities.
Golden-coloured rutile typically occurs in a slender acicular form. The small needles of rutile found in gems cause an optical phenomenon known as asterism. Asterated gems are known as "star" gems (Star sapphire, Star rubies, etc.).