Assertion: onyx's color | /r/HasSubevent | fading in sunlight
Facets:
value: in sunlight
type: LOCATION
Source sentences:
text: Prasiolite, or “greened amethyst” was produced in the 1950’s by heating yellowish quartz or light amethyst material from the Montezuma deposit in Minas Gerais, Brazil to 400-500ºC (900ºF±), but the delicate color is subject to fading in sunlight.