"Set me as a seal upon thine heart, as a seal upon thine arm: for love is strong as death" - Song of Songs 8:6a KJV
"They made the plate of the holy crown of pure gold, and wrote on it an inscription, like the engraving of a signet, 'Holy to the LORD.' And they tied to it a cord of blue to fasten it on the turban above, as the LORD had commanded Moses. Thus all the work of the tabernacle of the tent of meeting was finished, and the people of Israel did according to all that the LORD had commanded Moses; so they did." - Exodus 39:30-32 ESV
The engraving of permanence in the crown and the attachment of a cord of blue to the head dress was the last step. After that the tabernacle was finished.
Also, The engraving of a signet ring must not only be clear to the person inspecting the ring (this ring was like a credit card for families in ancient days)... it's imprint in wax had to be clear since that is what would be read on the contract after the one bearing the ring had left the room and traveled on.
We want the image of God's love to be on us and Him to set us on His heart (affections and thinking) and upon his arm (His power and working in the world).
Love is as strong as death. Death is the most permanent thing we know in this life. Even Christ who was raised from the dead (the one exception to the rule as yet) bears the marks of his death forever. Death remains on His record. It is a notch in His belt. The death He bore was our death and the life we now have is His life. Amazing.
His love has marked us with an image that can be traced back to Him alone. A trained eye sees the mark that only God's ring leaves imprinted in our lives. A permanent mark.
At the moment of the engraving and connecting of His cord this tabernacle was completed. Worship can now take place here. This body was made for worship that bears the stamp of Love.
The clear mark gives us access into the Holy place.