Assertion: blue topaz | /r/HasProperty | rare
Facets:
value: very
type: DEGREE
value: in nature
type: LOCATION
value: prior to this development
type: TEMPORAL
Source sentences:
text: Blue Topaz Is Rare In Nature
text: Naturally occurring blue topaz is quite rare.
text: Natural blue topaz is extremely rare and is usually pale blue.
text: Prior to this development, natural, light blue topaz was rare and valuable, while colorless topaz was common and could be purchased cheaply per ton.
text: Blue Topaz does occur in nature, but is rare and almost always lightly color.
text: Blue Topaz does occur in nature, but is rare and almost always lightly color.
text: Blue topaz in nature is very rare indeed and tends to be a very pale blue.
text: Naturally occurring blue topaz is quite rare.
text: Blue topaz, which is very rare in nature, can be made by irradiating and then heating clear topaz.
text: But natural topaz occurs mainly in white (colorless) and brown; natural blue topaz is actually very rare.
text: Almost all of the blue topaz sold today has been irradiated and then heated to produce a blue colour, because natural deep blue topaz is rare.
text: Blue Topaz does occur in nature, but is rare and almost always lightly colored.
text: Natural blue topaz is very rare and one of the sources of this rare variety of topaz is the Ural Mountains of Russia.
text: But natural topaz occurs mainly in white (colorless) and brown; natural blue topaz is actually very rare.