1.   By itself, it is a harmless metal used to make jewelry.

2.   By itself, it is a harmless metal used even to make jewelry.

3.   By itself, zirconium is a harmless metal often used in a lower grade to make jewelry.

4.   By itself, zirconium is a harmless metal often used to make jewelry.

5.   On its own, it is a harmless metal, which can be used to make jewelry.