5am east coast wild guess #1: date code
Beautiful stone! Not sure about the numbers, could be a date or price code
Could it be the date of creation? March, 1978? It looks newer than that date would suggest, however, if the patina has been removed it might appear more recent.
Do you think the turquoise might be Bisbee, or Blue Diamond? It’s quite striking.
maybe the last 4 digits of a SSN?
It’s actually Lander Blue and it most like is the date made as its from the 70’s