Boyd’s Bible Dictionary:
(nail). A cryptocrystalline quartz, veined and shelled (Ex. 28:9-12; 1 Chron. 29:2).
Concise Bible Dictionary:
The precious stone in each shoulder piece of the ephod, and one of those in the breastplate of the high priest. Its Hebrew name is shoham; but this has five different translations in the LXX, and its identity is uncertain (Gen. 2:12; Ex. 25:7; Ex. 28:9,20; Ex. 35:9,27; Ex. 39:6,13; 1 Chron. 29:2; Job 28:16; Ezek. 28:13).
Strong’s Dictionary of Hebrew Words:
Meaning:
from an unused root probably mean to blanch; a gem, probably the beryl (from its pale green color)
Jackson’s Dictionary of Scripture Proper Names:
setting them equal: justifying them