Then she has great taste--for thousands of years, Turquoise has been prized as a symbol of wisdom, nobility and immortality. Among the ancient Egyptians, Persians and Chinese, Aztecs and Incas, and Native Americans, Turquoise was sacred in its adornment and for power, luck, and protection. GL!
Like most American-Indian Sterling jewelery, it is not hallmarked. As you probably are aware, the tribes are not bound by US law in the regard so they usually do not hallmark their pieces.