About: http://webisa.webdatacommons.org/77909370

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Double refractive are aquamarine, sapphire, ruby, emerald, tourmaline, topaz or any of the quartz varieties such as amethyst, peridot & citrine.
http://www.w3.org/ns/prov#wasQuotedFrom	wordpress.com