Also see definition of "Amethyst" in Word Study
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Amethyst
Amethyst [EBD]
one of the precious stones in the breastplate of the high priest (Ex. 28:19; 39:12), and in the foundation of the New Jerusalem (Rev. 21:20). The ancients thought that this stone had the power of dispelling drunkenness in all who wore or touched it, and hence its Greek name formed from a_, "privative," and _methuo, "to get drunk." Its Jewish name, ahlamah', was derived by the rabbins from the Hebrew word halam, "to dream," from its supposed power of causing the wearer to dream.
It is a pale-blue crystallized quartz, varying to a dark purple blue. It is found in Persia and India, also in different parts of Europe.
AMETHYST [SMITH]
(Heb. achlamah) a subspecies of quartz of a bluish-violet color. Mention is made of this precious stone, which formed the third in the third row of the high priestly breastplate, in (Exodus 28:19; 39:12) It occurs also in (Revelation 21:20)Also see definition of "Amethyst" in Word Study