Exodus 29:28

²⁸ And it shall be Aaron's and his sons' by a statute for ever from the children of Israel: for it is an heave offering: and it shall be an heave offering from the children of Israel of the sacrifice of their peace offerings, even their heave offering unto the LORD.

Agate

In Exodus 28:19, it is not certain what kind of stone this was, but it was azure from white, which signifies spiritual good. It also signifies natural good, or that of the lowest heaven. (Arcana Coelestia 9870, True Christian Religion 609)

An agate, one of the precious stones in Aaron's breastplate, signifies the spiritual love of good (Exodus 28:19).