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黄玉(Topaz)

更新时间:2025-08-07 14:28:35

topazisahard,transparentmineral.itisacompoundofaluminum,silica,andfluorine.gemtopazisvaluable.jewelerscallthisvarietyofthestone"precioustopaz".thebest-knownprecioustopazgemsrangeincolorfromrichyellowtolightbrownorpinkishred.topazisoneofthehardestgemminerals.inthemineraltableofhardness,ithasaratingof8,whichmeansthataknifecannotcutit,andthattopazwillscratchquartz.

thegoldenvarietyofprecioustopazisquiteuncommon.mostoftheworldstopaziswhiteorblue.thewhiteandbluecrystalsoftopazarelarge,oftenweighingthousandsofcarats.forthisreason,thevalueoftopazdoesnotdependsomuchonitssizeasitdoeswithdiamondsandmanyotherpreciousstones,wherethevalueincreasesaboutfourtimeswitheachdoublingofweight.thevalueofatopazislargelydeterminedbyitsquality.butcolorisalsoimportant:bluetopaz,forinstance,isoftenirradiatedtodeepenandimproveitscolor.

bluetopazisoftensoldasaquamarineandavarietyofbrownquartziswidelysoldastopaz.thequartzismuchlessbrilliantandmoreplentifulthantruetopaz.mostofitisvarietyofamethyst:thatheathasturnedbrown.

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