Solid Chrome Steel Balls.
This is an expansion ofthe most popular sizes used by ring makers and should cover most of your needs. This set includes one ball each of the following:
1-1/16"
1"
7/8"
13/16"
3/4"
5/8"
6 Balls total
Be sure to store these in a dry place to prevent rust. It is best to keep a thin coat of oil such as WD-40 or 3-in-1 oil to maintain a long useful life.