Dan's stone was a species of topaz, in which was visible the inverted face of a man, for the Danites were sinful, turning good to evil, hence the inverted face in their stone.
The turquoise was Naphtali's stone, for it gives its owner speed in riding, and Naphtali was "a hind let loose."
Gad's stone was the crystal, that endows its owner with courage in battle, and hence served this warlike tribe that battled for the Lord as an admonition to fear none and build on God.
The chrysolite was Asher's stone, and as this stone aids digestion and makes its owner sturdy and fat, so were the agricultural products of Asher's tribe of such excellent quality that they made fat those who ate of them.